Biology- Unit 2- Book & lecture notes - Cancer & Genetics - ch 9, 10, 12

Treating Cancer For many types of cancer, the first line of treatment is ----to remove the tumor. In the case of breast cancer, that can be complete removal of the breast, called a mastectomy, or removal of just the tumor plus a small amount of surrounding tissue, called a lumpectomy. Surgery is generally effective for solid tumors that are ---, but not for cancers that have spread to other ----, or for cancers that ----, like leukemia. In these cases, the best option is usually chemotherapy—using toxic chemicals to kill the cancer cells in the body. Most chemotherapy drugs work by interfering with one or more steps of the ---- Doctors may also treat a tumor with radiation. In radiation therapy, beams of ionizing (high-energy) radiation are focused on a ---. The radiation damages ---. Cancer cells are less able to repair this DNA damage than are normal cells, and so they die. The downside of both chemotherapy and radiation is that they can cause severe side effects. That's because neither therapy is very specific—both treatments damage all dividing cells in their path, including healthy ones. Chemotherapy routinely kills healthy cells lining the intestinal tract, cells in hair follicles, and cells in the bone marrow—all of them cells that normally divide frequently. The side effects of these unintended cell deaths can include vomiting, bruising, hair loss, and susceptibility to infection. In recent years, new forms of cancer treatment have become more common, including targeted therapy and immunotherapy. Targeted therapies are designed to kill ---specifically, often by combating a specific defect in the cancer cell, such as the mutated protein made from an oncogene or tumor suppressor. For example, drugs called PARP inhibitors are an effective treatment for BRCA-mutated cancers, including breast, ovarian, and prostate cancers. PARP inhibitors block the activity of an enzyme that contributes to DNA repair. Normal cells with functioning BRCA proteins can repair DNA damage in the presence of PARP inhibitors, but BRCA-mutant cells cannot and consequently die. Women with HER2-positive breast cancer commonly receive the targeted drug Herceptin (trastuzumab), which blocks the action of the protein made from this oncogene. Targeted therapies exist for many other cancers, too, including Gleevec (imatinib mesylate) for certain leukemias and Zelboraf (vemurafenib) for BRAF-mutated melanoma. Immunotherapies are drugs or treatments that stimulate our own ----to find and fight cancer in the body. For some types of cancer—including melanoma, lung, and kidney cancer—this approach has proven to be very effective. There are several forms of immunotherapy. In one common approach, drugs are used to release a natural brake on immune cells that keeps the immune system in check. Once this brake is released, the immune cells can attack the cancer. Not everyone responds to these drugs, but those who do can sometimes experience dramatic results.

surgery diagnosed early parts of the body do not produce tumors cell cycle in dividing cells tumor DNA in dividing cells cancer cells immune system

CSI: DNA Fingerprinting

1- cut all dna samples with the Same enzyme 2- after PCR, place samples into a gel 3- compare

5 What are some differences and some similarities between tumor suppressor genes and oncogenes? 6 Which of the following can cause cancer to develop and progress?

5 In their nonmutant states, both tumor suppressor genes and proto-oncogenes are important for proper cell cycle progression. In their mutant states, both contribute to the development and progression of cancer. Normal tumor suppressor genes act to prevent the cell cycle from progressing inappropriately (e.g., when there is rampant DNA damage). When mutated, tumor suppressor genes can no longerpause the cell cycle when necessary, and cells with DNA damage may continue to divide. Normal proto-oncogenes act to promote cell division in response to appropriate signals to divide. When proto-oncogenes are mutated to oncogenes, they continuously "push" cells to divide, even in the absence of growth-promoting signals. 6 an oncogene and a mutated tumor suppressor gene

AMNIOCENTESIS KARYOTYPE

A procedure that removes fluid surrounding the fetus to obtain and analyze the chromosomal makeup of fetal cells. The chromosomal makeup of cells. Karyotype analysis can be used to detect chromosomal disorders prenatally.

MULTIFACTORIAL INHERITANCE ANEUPLOIDY NONDISJUNCTION TRISOMY 21 .

An interaction between genes and the environment that contributes to a phenotype or trait. An abnormal number of one or more chromosomes (either extra or missing copies). The failure of chromosomes to separate accurately during cell division; nondisjunction in meiosis leads to aneuploid gametes. Having an extra copy of chromosome 21; also known as Down syndrome

Eugenics 3- Positive Eugenics vs. 4- Negative Eugenics

Def: controlling human reproduction in a society to achieve a societal goal 1- genetically higher standards 2- term coined in 1883 3- provided incentives to genetically superior couples when they had children 4- preventing unstable people from having children

SEX CHROMOSOMES X-LINKED TRAIT PEDIGREE Y-CHROMOSOME ANALYSIS

Paired chromosomes that differ between males and females. Females have XX, and males have XY. A phenotype determined by an allele on an X chromosome. A visual representation of the occurrence of phenotypes across generations. The comparison of sequences on the Y chromosomes of different individuals to examine paternity and paternal ancestry.

How does one specialized cell type differ from another, and how do stem cells differentiate into these specialized cells?

This process, in which a stem cell develops into a more specialized cell type, is called cell differentiation Stem cells differentiate into specialized cells by turning some genes "on" and others "off." Through this unique pattern of gene expression (see Chapter 8), different cell types make different suites of proteins that are specific to those cell types. So while every cell in our body carries the exact same DNA, it is a cell's pattern of gene expression—and therefore the proteins produced from those genes—that defines it as one cell type or another.

How Old Are You?

Tissues are as old as the cells making them up. Cells in tissues are replaced when they wear out or reach the end of their life span. Scientists have dated the age of tissues in the human body and have found that some are much younger than you may think.

most of our tissues are in ----as cells divide periodically to replace cells that have reached the end of their life span.

constant flux

Although most individuals have internal and external genitalia that are either clearly male or clearly female, there are exceptions. Each year about 1 in every 1,500 babies born in the United States falls into an intermediate sex category termed "---." An intersex person is someone whose external genitalia do not match his or her internal sex organs or genetic sex—for example, a person with an XX chromosome pair who has internal ovaries but external genitalia that appear male. Also included in this category are babies born with ambiguous genitalia—for example, a penis that is very small or a clitoris that is exceptionally long.

intersex

Humans have 23 pairs of chromosomes

•One chromosome from each pair is inherited from the biological mother .•One chromosome from each pair is inherited from the biological father All Cells have All Chromosomes!

DNA evidence is more reliable than other forms of evidence

•Some evidence commonly presented in criminal cases can be unreliable. ▫Error rates for bite mark identification can be as high as 91%. ▫Hair analysis can only exclude a suspect, not positively identify one.

The structure of DNA: Nucleotide sequences

•The specific sequence of nucleotides along a strand of DNA is unique to each individual. Except for identical twins, no two people share exactly the sameDNA

Cancer prevention and treatment Treatments: 1- surgery 2- radiation 3- chemotherapy

1- Cut out tumor 2- kills cancer in specific area 3- kills cancer cells that have spread - drugs kill rapidly dividing cells - Side effects include hair loss, nausea, vomiting

12 Which of the following is/are differences between stem cells and mature, specialized cells? 13 Is the genome of stem cells larger than that of specialized cells?

12 a. most mature specialized cells do not divide b. stem cells can divide infinitely 13 no, because all cells in a person have an identical set of genes in their genome

15 People like Lorene Ahern have inherited a mutated version of BRCA1. Why does this mutation pose a problem? Why are these people at high risk of developing breast cancer when they still have a functional BRCA1 allele? Describe how the protein encoded by normal BRCA1 compares to that encoded by mutant alleles of BRCA1.

15 BRCA1 encodes a protein that plays an important role in DNA repair: it is a tumor suppressor gene. A BRCA1 mutation in one allele means that cells are relying on the other (functional) allele of BRCA1 If a subsequent single mutation disrupts that other allele of BRCA1, that single mutation is sufficient to eliminate all BRCA1 function in the cell. This is because mutant alleles of BRCA1 encode proteins that cannot function in DNA repair.

To prevent the negative use of eugenics in the future ... 1- Learning how to predict traits from a family tree 2- improve knowledge about what traits are genetically based and what traits are not 3- screen for carriers 4- treatment options available

2- scientists have sequenced the human genome 3- genetic testing 4- genetic therapy

5 Predict the sex of a baby with each of the following chromosomal makeups. Use your answer to check your answer to Question 1. a. XX b. XXY c. XY d. X 6 Consider your brother and your son. a- If you are female, will your brother and your son have essentially identical Y chromosomes? Explain your answer. b- If you are male, will your brother and your son have essentially identical Y chromosomes? Explain your answer. 7 A wife is heterozygous for Duchenne muscular dystrophy alleles, and her husband does not have DMD. Neither has any other notable medical history. What percentage of their sons, and what percentage of their daughters, will have a- Duchenne muscular dystrophy (which is determined by a recessive allele on the X chromosome)? b- an X-linked dominant form of rickets (a bone disease)?

5- a. female b. male (Klinefelter syndrome) c. male d. female (Turner syndrome) 6- a. Your brother and your son will not have the same Y chromosome. Your brother got his Y from his and your dad; your son got his Y from his dad which is your husband. b. You and your brother inherited the same Y chromosome from your dad, and you passed the same Y chromosome on to your son. 7- a. DMDis an X-linked recessive condition. If the mother is a carrier and the father does not have the disease, then 0% of the daughters will have Duchenne muscular dystrophy, and 50% of the sons will have the disease. b. As neither the mother nor the father has rickets, neither has an X-linked dominant allele of the rickets gene. Thus there are no dominant rickets alleles to transmit, and none of the children are at risk. 0%

6 A chemical is added to cells growing in a culture dish. This chemical blocks the completion of DNA replication. In what stage of the cell cycle will the cells be stuck? 7 Many drugs interfere with cell division. Why shouldn't pregnant women take these drugs? 8 What would be the result if a cell completed interphase and mitosis but failed to complete cytokinesis—how many cells would there be at that point, and how many chromosomes would those cells have in comparison to the parent cell?

6 Cells will not be able to complete DNA replication, so will be stuck at S phase 7 The embryo (and later the fetus) is growing by mitotic cell division. If the mother took a drug that interfered with cell division, that drug could interfere with normal development of the embryo and fetus, causing birth defects and possibly death of the developing baby. It effects embryonic development, wound healing, and replacement of blood cells 8 If a cell completed interphase and mitosis but then did not complete cytokinesis, the result would be a single cell with two nuclei. Each nucleus would have the same number of chromosomes as the parent cell. This means that the single binucleate cell would have twice the number of chromosomes as the parent cell. One; 46 chromosomes

9 You scraped your knee when you tripped over a curb playing Pokemon Go. As your injury heals, what cell type is likely to be dividing to replace the cells lost when you injured yourself? 10 In order to coax a stem cell to differentiate into a specific type of specialized cell, what has to happen? 11 Relative to one of your liver cells, one of your skin cells

9 stem cells in the skin/ skin cells 10 It must express a specific subset of genes They can't get "new" genes or get rid of other genes- They instead express a subset of genes needed to produce a unique set of proteins that make it distinguishable. 11 -has the same genome (the same genetic material) -has a different pattern of gene expression .All our cells have the same genetic material. Different genes are turned on or off during cell differentiation to develop tissues with different functions. (p. 206)

TUMOR CARCINOGEN MUTAGEN ALLELE

A mass of cells resulting from uncontrolled cell division. Any substance that causes cancer. Most carcinogens are mutagens. Any chemical or physical agent that can damage DNA by changing its nucleotide sequence. Alternative versions of the same gene that have different nucleotide sequences.

How does nondisjunction lead to numerical abnormalities of chromosomes, and what are the consequences of these abnormalities?

A numerical chromosomal abnormality means that a developing fetus carries a chromosome number that differs from the usual 46. The most common numerical abnormalities in humans are called aneuploidies, deviations from the normal number of chromosomes in which single chromosomes are either duplicated or deleted. Most aneuploidies arise during meiosis, as the parents' sex cells are being formed. If chromosomes do not separate properly during meiosis, an occurrence called nondisjunction, the resulting gamete will either lack a chromosome or carry an extra one. When that gamete is fertilized by a normal gamete, the resulting zygote can have an abnormal number of chromosomes. In most cases, the abnormality is so severe the zygote spontaneously aborts There are, however, cases in which the abnormality is not life threatening but does cause severe disability. The most common of these is trisomy 21, another name for Down syndrome. Trisomy 21 results when an embryo inherits an extra copy of chromosome 21. Anyone can conceive a child with the abnormality, but older women are at much higher risk.

Example of Point mutations ( or substitution) Antithrombin - A protein within our blood that helps prevent clotting What happens when you have a single point mutation with this?

The cytosine changes to a guanine and The anti-thrombin is going to have an ab normal shape - nonfunctional - possibly get thrombosis = prevent normal blood flow when the blood contains only abnormal proteins - problematic

MITOTIC SPINDLE STEM CELLS CELL DIFFERENTIATION

The microtubule-based structure that separates sister chromatids during mitosis Immature cells that can divide and differentiate into specialized cell types The process by which a cell becomes specialized to carry out a specific role by turning specific genes "on" and "off" and making different suites of proteins.

SISTER CHROMATIDS MITOSIS CYTOKINESIS CENTROMERE

The two identical DNA molecules that result from the replication of a chromosome during S phase. The segregation and separation of replicated chromosomes during cell division. The physical division of a cell into two daughter cells. The specialized region of a chromosome where the sister chromatids are joined; it is critical for proper alignment and separation of sister chromatids during mitosis.

Until recently, most bioprinters were simply modified ink jet printers with cartridges filled with cells instead of ink. The printers that now do this work are specifically designed and built for the purpose of making organs. They have different wells for different types of cells and the synthetic polymers that make up the biodegradable scaffold A second difficulty with engineering more-complex solid organs like livers, hearts, and kidneys is ensuring that all the cells in the organ are linked to an adequate ---. In normal tissues, an intricate web of capillaries supplies blood throughout the tissue (see Chapter 27). Without this blood supply, an engineered organ cannot be more than a centimeter or so thick—otherwise, the cells in the middle of the structure will die from lack of oxygen and nutrients. Cadavers could help, too. Cadaver-derived scaffolds have the advantage of retaining the body's natural design of channels and other spaces

blood supply

At age 25, a woman's risk of having a baby with Down syndrome is 1 in 1,250 births (that is, 1 out of every 1,250 babies born to women who are 25 is likely to have Down syndrome). At age 40 her risk skyrockets to 1 in 100 births. . All the eggs that a woman will ever have were formed before she was born, during fetal development, and they have been aging like the rest of the cells in her body. Until puberty, a woman's developing eggs are paused in the middle of ---(at meiosis I); they haven't yet completed their cell division. During a menstrual cycle, one of these cells resumes meiosis and is ovulated. In older women, as eggs complete meiosis and are ovulated, they are more likely to experience an error in chromosome segregation, leading to an abnormality of chromosome number in the egg.

meiosis

If cell division can repair a wound on our finger, why can't it repair a damaged body part or organ? Actually, in some cases it can. But these are the exceptions:

most human organs, including the bladder, cannot repair damage on their own.

To repair tissue damaged by injury or disease, stem cells must do more than simply divide repeatedly. The new cells must also go through a process of ---to develop into the specific cell types appropriate to the tissue in need of repair. Remember that during embryonic development a single cell becomes millions as the embryo grows. These dividing cells eventually become specialized as muscle cells, kidney cells, heart cells, and more than 200 other cell types by the time we are born. This process, in which a stem cell develops into a more specialized cell type, is called cell ---

specialization differentiation

1 What is Eugenics? 2 What types of traits can be inherited? 3 What does it mean to be recessive or dominant? 4 How do you interpret a pedigree? 5 Can you predict a person's genotype/phenotype?

- 1- Eugenics is the practice or advocacy of improving the human species by selectively mating people with specific desirable hereditary traits. It aims to reduce human suffering by "breeding out" disease, disabilities and so-called undesirable characteristics from the human population 2- In terms of heredity, and following this classification, the recipes that determine the characteristics or traits for each person are divided into AUTOSOMAL characteristics if they are contained in the first 22 sets of chromosomes -And SEX LINKED characteristics if they are part of set 23. Within this group, we will only work with those recipes or traits that are "X"-chromosome dependent, as this chromosome is shared equally by the male and the female's sex-chromosomes. When discussing these recipes, we will refer to them as traits or characters linked to the X-chromosome. Conversely, traits that are "Y"-chromosome dependent are only transmitted from male to male. 3- Dominant and recessive traits exist when a trait has two different forms at the gene level. The trait that first appears or is visibly expressed in the organism is called the dominant trait. The trait that is present at the gene level but is masked and does not show itself in the organism is called the recessive trait. -A DOMINANT character or trait is when only one of the two recipes is expressed, be it the mother's or the father's, with one dominating over the other -The other recipe that is not being expressed at this moment but that belongs to the same chromosomal set (although it did not manifest in the presence of the other recipe) is called RECESSIVE character or trait because it is in RECESS, overlapping or hidden. -When both recipes are identical and are present twice are called RECESSIVE characters or traits. -Now, the situation has changed and it is present twice, e.g. both recipes provide or codify the same type of information And, because neither dominates one over the other as they both carry the same contents, the trait WILL indeed express itself. In this instance, "blond hair". 4- - Pedigrees are used to analyze the pattern of inheritance of a particular trait throughout a family. Pedigrees show the presence or absence of a trait as it relates to the relationship among parents, offspring, and siblings. -Pedigrees represent family members and relationships using standardized symbols. -By analyzing a pedigree, we can determine genotypes, identify phenotypes, and predict how a trait will be passed on in the future. The information from a pedigree makes it possible to determine how certain alleles are inherited: whether they are dominant, recessive, autosomal, or sex-linked. To start reading a pedigree: 4.1- Determine whether the trait is dominant or recessive. If the trait is dominant, one of the parents must have the trait. Dominant traits will not skip a generation. If the trait is recessive, neither parent is required to have the trait since they can be heterozygous. 4.2- Determine if the chart shows an autosomal or sex-linked (usually X-linked) trait. For example, in X-linked recessive traits, males are much more commonly affected than females. In autosomal traits, both males and females are equally likely to be affected (usually in equal proportions). 5- -A Punnett square allows the prediction of the percentages of phenotypes in the offspring of a cross from known genotypes. A Punnett square can be used to determine a missing genotype based on the other genotypes involved in a cross.

What are mutations, and how can they occur?

. Mutations are changes in the nucleotide sequence of DNA. Women who are born with mutations in either of the two genes Ahern had tested have a much higher risk of developing breast and ovarian cancers; men with these mutations are at higher risk for breast and prostate cancers. Moreover, she could have passed on this mutation to her two children, putting them at risk.

Are tanning beds safe? 1- tanning salon owners say tanning machines are safer than outdoor tanning for two reasons: 2- UVA is a known carcinogen. - Scientific studies have revealed the tanning salons frequently exceed safe UV limits

1 - they mainly use UVA rays (still radiation) - they offer more controlled UV exposure 2- tanning beds increase the risk of skin cancer

1 What are the main types of mutations? 2 Are all mutations bad? 3 How does our body deal with mutations? 4 What is cancer? 5 How do human cells divide with mitosis? 6 What is the difference between malignant and benign tumors? 7 What are carcinogens? 8 How does tanning affect our skin? 9 What is a DNA fingerprint? 10 How can scientists determine paternity? 11 What does this mean for my health?

1 - frameshift mutations - changes the grouping of nucleotides base and shifts the reading frame - Point mutations ( or substitution) - Single nucleotide base changes in the genes DNA sequence 2 most are harmless or neutral and have no impact on protein production 3 During The proof-reading stage (the change in DNA), Most mutations are caught. Cells are destroyed and the mutation is eliminated (apoptosis - self suicide) -However, mistakes occur and-don't catch errors 4 unregulated cell division - in cancer cells, the checkpoint genes have mutations and loss of cell cycle control - in normal cells, we have tumor suppressors (TS) = Gene suppress (stop) cell division and... - Proto-oncogenes, (PO) normally introduced (start) cell division intermediately - gas peddle -In cancer: 1- TS: No brakes ( has a mutation) 2- PO: gas pedal is stuck (mutation) - cells are constantly being told to divide 5 During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. ... Meiosis also allows genetic variation through a process of DNA shuffling while the cells are dividing. - During mitosis one cell divides once to form two identical cells. - The major purpose of mitosis is for growth and to replace worn-out cells. - If not corrected in time, mistakes made during mitosis can result in changes in the DNA that can potentially lead to genetic disorders?. 6 tumors can be benign (noncancerous) or malignant (cancerous). - Benign tumors tend to grow slowly and do not spread. - Malignant tumors can grow rapidly, invade and destroy nearby normal tissues, and spread throughout the body. 7 substances that increase random mutations that lead to cancer -something that can cause you to have cancer. It may be a substance in the air, a product you use, or a chemical in foods and drinks. 8 Tanning damages your skin cells and speeds up visible signs of aging. Worst of all, tanning can lead to skin cancer. It's a fact: There is no such thing as a safe or healthy tan. Tanning increases your risk of basal cell carcinoma, squamous cell carcinoma and melanoma. 9 DNA fingerprinting is a method used to identify an individual from a sample of DNA by looking at unique patterns in their DNA. -DNA fingerprinting is a technique that simultaneously detects lots of minisatellites (short tandem repeats (STRs)) in the genome to produce a pattern unique to an individual. This is a DNA fingerprint. 10 In a DNA paternity test, DNA samples from two possible fathers and the mother are compared with the offspring's DNA. ... The digested DNA is loaded onto a gel and separated according to size, by gel electrophoresis. Every band of the offspring's DNA must match a band in at least one of its parents'.. 11

Heredity, behaviors, other factors? - different cancers 2- limit alcohol and tobacco 3- chemicals in radiation that are capable of triggering the development cancers are called. Percentigens

1 - Studies from one country and another suggest that exposures to risk factors for cancer is vary from different locations 2- alcohol increases your risk of various cancers especially those of the mouth, the throat, and the esophagus - The combination of alcohol and tobacco is especially dangerous - for heavy smokers or for heavy drinkers, the risk for developing cancers is six times of that of that from A non-smoker or drinker - it is 40 times the risk for heavy alcohol and tobacco users then it is for non-smokers and drinkers 3- percentigens - act through this multi step process that initiates The series of genetic alterations or mutations - they also stimulates cells to Praliferate for a long period of time ( longe period until cancer catches up to you= lag time)

1 What process is critical for embryonic development, wound healing, and replacement of blood cells. 2 In the cell cycle, DNA is replicated during a -mitosis. b- G1. c- S. d- G2. e- cytokinesis. 3 Following mitosis and cytokinesis, daughter cells 4 During which stage of the cell cycle do sister chromatids separate from each other? 5 During which stage of the cell cycle are sister chromatids initially produced?

1 Cell division (mitosis and cytokinesis) 2 c- S. 3 Genetically identical to each other and genetically identical to parent cell 4 Anaphase of mitosis 5 S-phase/ interphase

Can there be a partial match? 1 •DNA Fingerprinting: 2•Compare the banding pattern 3•Paternity Testing 4Each of us inherited one copy of EVERY chromosome from each parent: one from Mom, and one from Dad

1 Determining Relation 2 ▫The more similar the DNA, the more similar the sizes of the DNA fragments, the more likely the individuals are related 3 ▫Determines Paternity of a baby (after birth) 4 As a result, each of our cells has pairs of chromosomes.

1 Frameshift mutations: 2 True or False: Chemotherapy causes hair loss because hair follicles divide rapidly, like cancer cells. 3- Which of following statements incorrectly identifies how cancer cells differ from normal cells? 4- picture 5- The genes that encode the proteins regulating the cell cycle are called ________.

1 Include insertion and deletion mutants 2 True 3 - Cancer cells form benign tumors.- false - Cancer cells make up malignant tumors- correct 4- picture 5- Proto-oncogenes

1 What would you predict would be the biological sex of a person born with two X chromosomes and a Y chromosome? 2 Red-Green Color blindness is most commonly associated the result of inheriting recessive alleles of specific genes on the X chromosome. A woman and her husband both have the same type of red-green color blindness. Predict thte frequencies of sons and daughters with red-green color blindness that this couple would have. 3 Imagine that Irene married Maurice instead of Prince Harry. What would you predict about their sons and daughters? (Reference Infographic 12.3 from your textbook to help you answer this question) 4 A male has a particular dominant allele F on this Y chromosome. Which of his children (sons and/or daughters) will inherit this allele)? 5 Familial hypercholesterolemia (FH) is an incomplete dominant characteristic. A woman has the severe form of FH (HH), and her husband does not has FH as all (hh). What proportion of their children will have severe FH, Mild FH, and/or no FH? 6 ABO blood type is a codominant characteristic. Why blood type exemplifies codominance? 7 Which of the following can result in Trisomy 21?

1 Male 2 All Children would have red-green color blindness 3 50% of all chlidren would have hemophilia 4 Only his sons 5 100% mild 6 AB 7 -an egg with 24 chromosomes (two of which as chromosome 21) fertilized by a sperm with 23 chromosomes -an egg with 23 chromosomes fertilized by a sperm with 24 chromosomes (two of which as chromosome 21)

1 A mutation causes a substitution of one amino acid for another in the encoded protein. What type of mutation is this? 2 Which of the following is a known mutagen? a. cigarette smoke b. sunlight c. charred meat cooked at high temperatures d. X-rays e. all of the above 3 Why does wearing sunscreen reduce cancer risk? 4 In an otherwise normal cell, what happens if one mistake is made during DNA replication?

1 missense 2 e. all of the above 3 Sunscreen can reduce the chance of mutations caused by exposure to UV radiation present in sunlight. 4 A cell cycle checkpoint detects the error and pauses the cell cycle so the error can be corrected.

Scientists have discovered more than ---in the general population, but most of them are rare. In Ashkenazi Jews, however, the prevalence of some of these diseases is increased 100-fold or more. Tay-Sachs disease, Gaucher disease, and Bloom syndrome are genetic diseases that all occur more frequently in this ethnic group than in the general population; approximately 1 in 25 Ashkenazi Jews carries disease alleles for at least one of these disorders Ashkenazi Jews are not the only ethnic group to have a higher incidence of certain genetic diseases than occurs in the general population. For example, people from Mediterranean, African, and Asian countries have higher rates of thalassemias—blood disorders that cause anemia. Sickle-cell anemia, another type of hereditary anemia, is more common among people of African descent. And the Amish have higher than typical numbers of people with polydactyly—having more than the typical number of fingers or toes—in this case, the result of Ellis-van Creveld syndrome, which has a genetic cause.

1,000 genetic diseases

Alleles 1- type of alleles: 2- note 3- A few exceptions

1- - dominant: The allele that is expressed if at least one is present - recessive: The wheel is only expressed if there are two copies present 2- - do not confuse with good/bad - do not confuse with how common a trait is 3- - incomplete dominant: both alleles are mixing together and showing (Red flower + white flower= pink flowers) - Codominant: both dominant and both expressed independently (not mixing) (The peppermint rose) - ex: blood type- IA, IB, I- (A and B are co-dominance and O is recessive)

1- A eugenics catechism- 1926 2- - required sterilization of mentally ill and criminal males - booths were set up at state and world fairs 3- - issues

1- - if defendants of two tainted people were cared for by the states, it costs the state= 2 million - if the original couple were sterilized through negative eugenics = 150 3- -what classified individuals as tainted or genetically superior? -

Eugenics 1- nazis took this idea 2- A further step 3- nordic ring: (this is a subset of the Nazi party) 4- The big issue with eugenics

1- - sterilized people of poor genetic worth - individuals included epilepsy, schizophrenia, blindness, alcoholism 2- - euthanasia - birth defects, mentally retardation 3- - attempted to create a master race 4- - not all trades selected for where genetically based! - sterilizing people with traits that cannot be passed down - sterilization lifted in US in 1956 (stopped negative eugenics)

1 Which of the following most influences the development of a female fetus? a- the presence of any two sex chromosomes b- the presence of two X chromosomes c- the absence of a Y chromosome d- the presence of a Y chromosome e- either b or c 2 Why are more males than females affected by X-linked recessive genetic diseases? 3 If a man has an X-linked recessive disease, can his sons inherit that disease from him? Why or why not? 4 Which of the following couples could have a boy with Duchenne muscular dystrophy (DMD)? a- a male with Duchenne muscular dystrophy and a homozygous dominant female b- a male without Duchenne muscular dystrophy and a homozygous dominant female c- a male without Duchenne muscular dystrophy and a carrier female d- a and c e- none of the above

1- c-the absence of a Y chromosome 2 Because males have a Y chromosome that does not represent the same alleles as the X chromosomes and cannot mask the X-linked recessive allele// because females have an additional X chromosome to mask the X-linked recessive allele 3 No, all his sons inherit their X chromosomes maternally. 4 c- A male without DMD and a carrier female

Cancer prevention and treatments Prevention:

1- Avoid exposure to carcinogens 2- sunscreen - some skin cancers are easy to cure 3- maintain a healthy diet 4- Exercise - Exercise keeps Immune system healthy - exercise helps prevent obesity 5- Treatment - early detection is key 6- Cancer screenings - Brest self exams, skin checks, Pap smears, prostate screening, colonoscopy 7- melanoma screening A- asymmetry B- border (Enlarged or irregular borders) C- Color (multiple colors) D- diameter ( bigger than a pencil eraser) E- elevation

What is cancer? - in cancer cells, the checkpoint genes have mutations and loss of cell cycle control 1- often takes a long time to develop 2- this is why cancer is more common in middle age and elderly people

1- It usually requires at least four different mutations (usually 5) before a person develops cancer - mutations in both tumor suppressor and proto-oncogenes genes

1- In normal cells Checkpoints:

1- The cell cycle has checkpoints to control cell division Checkpoints: 1- cell size checked to see if it has grown and big enough to support DNA replication - if it has not grown to the right size than the cell cycle can stop - end of G1 phase - if the sale does not check this point then it goes through apoptosis or cell cycle is stopped 2- DNA replication checked - end of second growth cycle (G2) - right before mitosis - checking to see if the cell has grown big enough to support dividing into two cells - if it sells not big enough or does not have enough cytoplasm then it cannot pass through this stage and stop division - check to see if DNA replication was done properly- checking for mistakes/ mutations 3- final - mitosis checked - after mitosis - Make sure everything was divided properly - check to see if each daughter cell is the exact copy of the original cell - if it passes all these checkpoints in the cell cycle passes

Example of Point mutations ( or substitution) - can change your blood type shape Sickle cell Amenia 1- The gene for 2- —-base pair change 3- —-amino acid change 4- sickle cell—- Sickle cell: 1- causes — 2- helps prevent—-

1- The gene for Hemoglobin ( A gene that carries oxygen in our blood system throughout our body and into our organs) however with sickle cell, the hemoglobin is not as functional. Does not carry oxygen as well and can starve our organs. Can cause affixation within our blood 2- One base pair change 3- One amino acid change 4- sickle cell phenotype Sickle cell: 1- causes blood clotting 2- helps prevent malaria (a positive)

Cell cycle 1- what is a cell cycle? 2- The three steps: 2.1- interphase (G1, S, G2) 2.2- mitosis 2.3- cytokines

1- The lifecycle of the cell 2.1- DNA replicates - The growth cycle - The synthesis cycle - another growth stage 2.2- copied chromosomes are moved into daughter cells 2.3- cell is split into two daughter cells

Common mistakes and misconceptions; Pedigrees

1- The presence of many affected individuals in a family does not always mean that the trait is dominant. The terms dominant and recessive refer to the way that a trait is expressed, not by how often it shows up in a family. In fact, although it is uncommon, a trait may be recessive but still show up in all generations of a pedigree. 2-You may not always be able to determine the genotype of an individual based on a pedigree. Sometimes an individual can either be homozygous dominant or heterozygous for a trait. Often, we can use the relationships between an individual and their parents, siblings, and offspring to determine genotypes. However, not all carriers are always explicitly indicated in a pedigree, and it may not be possible to determine based on the information provided.

What we know about UV 1- UV light is a form of radiation 2- radiation causes mutations in the DNA in skin cells 3- these mutations can lead to... 4- other effects:

1- UVA, UVB, UVC 2- T - T Dimers - T binds with T mutations 3- melanoma, basal cell carcinoma, or squamous cell carcinoma (skin cancers) - melanoma is the most dangerous and the most common in fair skin. Only 5% likely to get Melanoma skin cancer but they cause 75% of the deaths within skin cancers - basal cell carcinoma is more found on fair skin - squamous cells are commonly found in dark skin - basal cell and squamous cell are less likely to metastasize so they are considered "good" cancer and less likely to spread 4- wrinkles, saggy skin, and sunspots

1- Cancer happens when... 2- what is cancer? 3- cancer cells differ from normal cells:

1- cancer happens when the cell cycle spins out of control - can't stop this - this is why we get tumors 2-unregulated cell division 3- cancer cells differ from normal cells: -divide when they shouldn't -invade surrounding tissues (stealing resources away from those surrounding tissues) - causes harm to them - move to other locations in the body (spread/ metastasizes)

Best studied antioxidants 1- beta carotene found in 2- vitamin C found in 3- vitamin E found in 4- selenium found in

1- carrots, sweet potatoes, pumpkin, cantaloupe, broccoli 2- Citrus fruits, asparagus, broccoli, brussels sprouts, bell peppers, Keewee, strawberries and tomatoes 3- nuts, seeds, almonds, vegetable oil, and whole grains 4- seafood, lean meats, chicken, low-fat dairy products and whole grains

The types of mutations that slipped through 1- frameshift mutations - Changes the Causes: 1.2- insertion mutations 1.3- deletion mutations 1.4- usually destroys the protein Example:

1- changes the grouping of nucleotides base and shifts the reading frame 1.2- add one or more DNA bases 1.3- remove one or more DNA bases 1.4 - changes many amino acids - add a stop codon: protein is not made - changes shape of proteins - detrimental Example: - ThesunwashotbutTheoldmandidnotgethishat Split into codons: - The sun was hot but The old man did not get his hat Shift the reading frame: - t he unw ash otb utt heo Idm and idn otg eth at. - or... - Th esu nwa sho Tbu tth eol dma ndi Dno tge thi t

Making a DNA Fingerprint: Step 1 - somatic cells not gamete/ sex cells Making a DNA Fingerprint: Step 2 Making a DNA Fingerprint: Step 3 4 DNA Fingerprinting

1- collect cells and extract DNA from crime scene evidence, ex = white blood cells, cheek cell in salive, slin cells - we cut up out enzymes - we need the same enzyme fir different people to compare 2 Use PCR to copy the DNA until we have enough available for testing - then we amplify the amount of DNA ▫each cycle of PCR, double the amount of DNA - we use PCR to make enough copies to measure - it's messy and tiny and this mixture-contains a lot of DNA fragments 3 Gel electrophoresis = DNA samples (cut into pieces) are placed in a gel - small fragments move faster then bigger - put known DNA sample into the ladder - sizes separate large to small - start to see banding pattern and u then compare 4 Each person will have a unique pattern of bands.

What happens when mutations occur 1- most are harmless or neutral 2- few are positive - example: 3- few are negative - example:

1- have no impact on protein production 2- Double jointed (helps with video game playing) - we see this often and it's how we get diversity 3- cancer

What are some risk factors for cancer 1- some mutations may be inherited 2- most are acquired during a persons lifetime

1- hereditary: 5% of breast cancers 2- exposure to carcinogens (cancer causing agents) - responsible for triggering most human cancers - example: radium watch painters

free radicals 1- oxygen atoms - two oxygen atoms share for electrons so both atoms will be stable - but if these two atoms split... 2- what causes free radicals to form? 3- why worry about free radicals? - involved in aging 4- stop the free radicals - antioxidants

1- highly reactive and will quickly steal electrons from the closest available atom - like those in DNA molecules - creates a chain reaction - odd number of electrons - then other atoms with stolen electrons become unhappy and steal from others 2- diet - UV light -Smoking - fatty foods - beer - air pollution 3- Gray hair, baldness, wrinkles - can you take your DNA leading to cancer - can damage and clog your arteries - can cause dandruff and hangovers - can cause loss of memory, hearing and sight 4- donate extra electrons to free radicals - blue barriers - now that they are stable, it stops the free radicals from stealing electrons and damaging our bodies - however, antioxidants from food can't counterbalance the free radicals we are exposed to in our environment - reduce your exposure to negative environmental factors -5-8 servings of fruit and vegetables. The deeper and brighter the color, the better

Other possibilities of allele combinations

1- homozygous dominant - AA 2- homozygous recessive - aa 3- heterozygous - Aa

Combating UV exposure - The skin naturally combat mutations by producing melanin (Brown pigment) Block UV radiation 1- darker skin offer is greater protection than light skin against sunburn and skin cancer

1- however, that applies only to people with naturally dark skin - tanning equals skin damage - tanning or sunburn, attacks the skin's DNA - tanning deplete natural folic acid levels

1- Inherit 2- The traits you are born with 3- environmentally caused mutations are not passed on to offspring 4- we get two alleles 5- what happens if the two alleles are not the same?

1- inheritable traits are coded in DNA 2- - exceptions: - Single event mistakes in meiosis are not often passed on (because extra /missing DNA) -Ex: - crossing over, independent assessment 3- - these are not the same in every cell - exception: - mutations occurring in eggs and sperm (you can pass this along) 4- - One from mom and one from dad 5- - ... next slide

Pseudoscience at work 1- tanning bed claims - Industry is claiming there is a doctor and government cover-up 2- attacking sunscreen - promoting vitamin D outside salons

1- marketing false claims for payment - claim that tanning does not causes melanoma 2- cannot legally make health claims

Why does cancer kill? 1- tumor 1.2- benign tumor: 1.3- malignant tumor: 1.4- metastasis: - cancer cells: - transported by: - reinvade:

1- mass of cells with no function 1.2- does not affect surrounding tissues (not cancer) - examples are warts - benign is fine 1.3- invades surrounding tissues; cancerous 1.4- cells break away from a malignant tumor and start a new cancer at another location - invade and corrupt surrounding tissues - transported by circulatory system to distant sites - re-invade and grow and new locations - especially bad for liver, heart, brain - when it metastasizes it is stage four cancer

Cell Cycle: - Interphase: - The DNA in the cell is copied in preparation for cell division, this results in two identical full sets of chromosomes. - Outside of the nucleus are two centrosomes, each containing a pair of centrioles, these structures are critical for the process of cell division. - During interphase, microtubules extend from these centrosomes. THEN: Mitosis 1- produces: 2- Four stages:

1- produces genetically identical daughter cells 2- 2.1 -prophase,: - The chromosomes condense into X-shaped structures that can be easily seen under a microscope. - Each chromosome is composed of two sister chromatids, containing identical genetic information. - The chromosomes pair up so that both copies of chromosome 1 are together, both copies of chromosome 2 are together, and so on. - At the end of prophase the membrane around the nucleus in the cell dissolves away releasing the chromosomes. - The mitotic spindle, consisting of the microtubules and other proteins, extends across the cell between the centrioles as they move to opposite poles of the cell. 2.2 - metaphase; - The chromosomes line up neatly end-to-end along the centre (equator) of the cell. - The centrioles are now at opposite poles of the cell with the mitotic spindle fibres extending from them. - The mitotic spindle fibres attach to each of the sister chromatids. 2.3 - anaphase; -The sister chromatids are then pulled apart by the mitotic spindle which pulls one chromatid to one pole and the other chromatid to the opposite pole. 2.4 - telophase; -At each pole of the cell a full set of chromosomes gather together. -A membrane forms around each set of chromosomes to create two new nuclei. -The single cell then pinches in the middle to form two separate daughter cells each containing a full set of chromosomes within a nucleus. This process is known as cytokinesis.

Mutations 1- can impact 2- can affect 3- when does mutation occur? At what stage? 4- why do mutations slip through?

1- protein synthesis 2- function and phenotype - can impact cell division 3- The proof-reading stage (the change in DNA) - Most mutations are caught - cells are destroyed and the mutation is eliminated (apoptosis - self suicide) 4- because sometimes the mutations don't have any affect (net neutral) - sometimes it is also due to mistakes -don't catch errors

Carcinogens 1- def: - ex:

1- substances that increase random mutations that lead to cancer - environmental (a big wasy to get them): sun's UV rays, pollutants, radium, x-rays - diet and lifestyle: - Foods high in free radicals, cigarettes, marijuana, excessive alcohol - viruses and bacteria - human papillomavirus (HPV)

Cancer linked viruses 2- HPV - Family of over 100 strain 3- 80% of women who have sex will acquire the virus by age 50 4- HPV vaccine

1- viruses inserts and changes genes for cell growth - The viral genetic information carried in the nucleic acid's Is inserted into the chromosomes of The infected cell and this causes the cell to be malignant 2- 10 can cause cervical cancer - can also lead to throw in mouth cancer in men 4- for female ages 9 to 26 - ideally before first sexual contact - now it is also recommended for males

Population-based studies

1- we can identify various causes of cancers by studying populations and behaviors 2- compares cancer rates to various populations and groups and different environmental factors and behaviors 3- surprising find is that cancer arises with different frequencies in different areas of the world

Why do alleles matter?

1- we can use this knowledge about alleles to predict the traits our kids might have 2- Gregor Mendel (1822 - 1884) - monk - first to identify the predictive power of inheritance

DNA Fingerprinting 1•Compares DNA sequences between individuals to prove or disprove a genetic relationship. 2 Identification Uses:

1- ▫Small differences in nucleotide sequences of their DNA 2 1. Criminal investigations 2. Paternity Analysis 3. Historical Analysi

Genotypes v. phenotypes Example: dwarfism

1-Aa - each child will be heterozygous for dwarfism 2- The genotype is the genetic code - Aa or - heterozygous 3- The phenotype is the physical appearance - dwarfism

12 Which of the following family histories most strongly suggests a risk of inherited breast cancer due to BRCA1 mutations? 13 A 28-year-old male graduate student was born with an inherited predisposition to colon cancer due to a mutation in a DNA repair gene called MLH1. He has recently been diagnosed with colon cancer. At the cellular and genetic level, was he born with colon cancer? Was he born with a predisposition to colon cancer? At birth, were cells in his colon genetically identical to cells in his liver? Now that he has colon cancer, are his cancer cells genetically identical to his normal colon cells? Explain your answers. 14 Which of the following women would be most likely to benefit from genetic testing for breast cancer? a.) a 25-year-old woman whose mother, aunt, and grandmother had breast cancer b.) a healthy 75-year-old woman with no family history of breast cancer c.) a 40-year-old woman who has a cousin with breast cancer d.) a 55-year-old woman whose older sister was just diagnosed with breast cancer e.) All women can benefit from genetic testing for breast cancer.

12 many female relatives with both early breast cancer and ovarian cancer 13 He was not born with colon cancer, but with a genetic predisposition to colon cancer. At birth, his colon cells were identical to his liver cells; they all had one normal copy of MLH1 and one mutated copy of MLH1 It would thus require a single mutation in the nonmutated MLH1 allele in a colon cell to allow that cell to progress to colon cancer. Now that he has colon cancer, both copies of the MLH1 gene in his cancer cells have the mutation, while his normal colon cells still have one normal copy and one mutated copy of MLH1 14 a 25-year-old woman whose mother, aunt, and grandmother had breast cancer

13 If two women have identical alleles of the suspected more than 400 height-associated genes, why might one of those women be 5 feet, 5 inches tall and the other 5 feet, 8 inches tall? 14 From what you have read in this chapter, how can you account for two people with the same genotype for a predisposing disease allele having different phenotypes? 15 What is the normal chromosome number for each of the following? a. a human egg b. a human sperm c. a human zygote 16 When looking at a karyotype, for example to diagnose trisomy 21 in a fetus, is it possible to use that analysis also to tell if the fetus has inherited a cystic fibrosis allele from a carrier mother? 17 Which of the following can result in trisomy 21?

13 The environment can influence height. If the two women did not have the same diets and nutrition while growing up, they may not reach the same height. Similarly, if one of the women develops osteoporosis, she may lose height over time. 14 The two people could have different alleles at other genes that influence the phenotype, or they could have different environmental influences (e.g., diet, stressful experiences, sun exposure) that could influence their phenotype. 15 a. 23 chromosomes b. 23 chromosomes c. 46 chromosomes 16 Karyotype analysis can be used to detect trisomy 21, as an extra chromosome is easily visible at this level. However, cystic fibrosis is caused by mutations that change the nucleotide sequence of the gene- these cannot be detected by simply looking at the chromosomes. 17 c. an egg with 24 chromosomes, two of which are chromosome 21, fertilized by a sperm with 23 chromosomes and d. an egg with 23 chromosomes fertilized by a sperm with 24 chromosomes, two of which are chromosome 21

14 What are the pros and cons of receiving an organ transplant versus growing a replacement organ from one's own cells? 15 Nerve cells (neurons) are highly specialized and generally don't divide. How does this characteristic help explain the severity of spinal cord injuries? 16 Cancer chemotherapy can damage the epithelial cells that line the digestive tract, leading to nausea and vomiting. These symptoms generally resolve after chemotherapy. What cell type is likely responsible for the regeneration of the lining of the digestive tract?

14 Pro: If a donor organ is available, it can be transplanted immediately, without the need to wait for an organ to be grown from one's own cells. Con: the often very long wait time to receive a matching organ; the possibility of immune rejection (even "matched" organs are not in fact a perfect match); the need for long-term immunosuppressive drugs that can leave a person vulnerable to infections (organs grown from a person's own cells will be a perfect match, so there is no concern about rejection and no need for immunosuppressive drugs). 15 Spinal cord injuries can destroy neurons. As the remaining neurons generally don't divide to replace the damaged ones, the injury generally does not repair. 16 stem cells

Types of mutations 2 2- Point mutations ( or substitution) Causes: 2.1- missense mutations 2.2- nonsense mutations 2.3- silent mutations

2- Single nucleotide base changes in the genes DNA sequence - A base pair is substituted with another base pair - The nucleotide is still present and it's not changing the reading frame. It's a (swap) 2.1- results in a single amino acid change within the protein - May or may not change the protein. It depends on which amino acid changes 2.2- create a premature "translation stop signal" or "stop" codon, causing the proteins to be shortened - causes a protein to be non-functional - detrimental 2.3- do not cause amino acid changes within the protein - if the third nucleotide gets substituted then it might not make any change within the protein - some wiggle room - Might not impact the protein at all

in normal cells 2- tumors 3- Proto-oncogenes In cancer 1- TS: 2- PO:

2- in normal cells, we have tumor suppressors (TS) = Gene suppress (stop) cell division - Gene to tell your cells to stop cellular division if there is something wrong - if there is DNA damage, it's going to stop and go into a Apoptosis (cell suicide) 3- Proto-oncogenes, (PO) normally introduced (start) cell division intermediately - gas peddle In cancer: 1- TS: No brakes ( has a mutation) 2- PO: gas pedal is stuck (mutation) - cells are constantly being told to divide

7 Which form of breast cancer treatment is the least specific for the cancer cells? a. chemotherapy b. immunotherapy c. targeted therapy d. lumpectomy 8 What would you say to a niece if she asked you how she could reduce her risk of breast cancer? (Assume there is no family history of breast cancer.) How might each of your suggestions reduce her risk? 9 Why is age a risk factor for cancer? 10 A woman with a BRCA1 mutation 11 What is the role of BRCA1 in normal cells?

7 d. lumpectomy 8 Reduce alcohol consumption.Utilize early screening.Avoid tobacco, Reduce sun exposure 9 It takes several mutations in the same cell for the cell to become cancerous. The older a person is, the more time in which a number of potentially cancer-causing mutations can be acquired. These can be the result of the greater number of cell divisions, as well as longer exposure to environmental carcinogens. 10 is at increased risk of developing breast cancer. 11 BRCA1 is a tumor suppressor gene that encodes a protein involved in DNA repair of mutations.

8 What aspects of height make it a polygenic trait? 9 Which of the following inheritance patterns includes an environmental contribution? 10 What is the difference between polygenic inheritance and multifactorial inheritance? 11 How does incomplete dominance differ from codominance? 12 If you are blood type A-positive, to whom can you safely donate blood? Who can safely donate blood to you? List all possible recipients and donors and explain your answer.

8 Many genes contribute to height. As there are multiple genes contributing to the phenotype, height has a polygenic component. 9 d. multifactorial 10 In polygenic inheritance, multiple genes influence the phenotype. Multifactorial traits are those on which environment has an influence. 11 In incomplete dominance, heterozygotes have a phenotype that is intermediate between the phenotypes of the homozygous dominants and the homozygous recessives. -Because both blood types have equal contribution. In incomplete dominance only one allele has dominance. In co-dominance, heterozygotes display traits of both alleles present 12 If you are type A-positive, then you can DONATE to other A-positive people, as well as to AB-positive people. If you are A-positive, you can RECEIVE type O-negative, O-positive, A-positive, and A-negative blood.

IMMUNOTHERAPY MAMMOGRAM

A cancer therapy that uses the immune system to recognize and destroy cancer cells An X-ray of the breast.

MALIGNANT TUMOR METASTASIS CONTACT INHIBITION ANCHORAGE DEPENDENCE

A cancerous tumor whose cells can spread throughout the body. The spread of cancer cells from one location in the body to another A characteristic of normal cells that prevents them from dividing once they have filled a space and are in contact with their neighbors. The need for normal cells to be in physical contact with another layer of cells or a surface.

MUTATION CANCER CELL CYCLE CHECKPOINT APOPTOSIS

A change in the nucleotide sequence of DNA. A disease of unregulated cell division: cells divide inappropriately and accumulate, in some instances forming a tumor. A cellular mechanism that ensures that each stage of the cell cycle is completed accurately. Programmed cell death; often referred to as cellular suicide.

INCOMPLETE DOMINANCE CODOMINANCE CONTINUOUS VARIATION POLYGENIC TRAIT

A form of inheritance in which heterozygotes have a phenotype that is intermediate between the two homozygotes. A form of inheritance in which the effects of both alleles are displayed in the phenotype of a heterozygote. Variation in a population showing an unbroken range of phenotypes rather than discrete categories. A trait whose phenotype is determined by the interaction among alleles of more than one gene.

PROTO-ONCOGENE TUMOR SUPPRESSOR GENE ONCOGENE BENIGN TUMOR

A gene that codes for a protein that helps cells divide normally. A gene that codes for a protein that monitors and checks cell cycle progression. When these genes mutate, tumor suppressor proteins lose normal function. A mutated and overactive form of a proto-oncogene. Oncogenes drive cells to divide continually. A noncancerous tumor whose cells will not spread throughout the body.

Historical DNA

Able to sequence dna from animals on verge of extinction and help with cloning, bring them back Might bring some stuff back Compare human dna to past species from dna in fossil fibers Can't bring back dinosaurs because dna is degraded

TISSUE CELL DIVISION CELL CYCLE INTERPHASE

An organized group of different cell types that work together to carry out a particular function. The process by which a cell reproduces itself; cell division is important for normal growth, development, maintenance, and repair of an organism. The ordered sequence of stages through which a cell progresses in order to divide; the stages include preparatory phases (G1, S, G2) and division phases (mitosis and cytokinesis). The stage of the cell cycle in which dividing cells spend most of their time, preparing for cell division. There are three distinct subphases: G1, S, and G2.

inheriting certain ---dramatically increases the risk of cancer, but it doesn't mean that the disease will necessarily develop. In most cases, hereditary cancer occurs only when ----in a cell accumulates. Similarly, the accumulation of harmful acquired mutations in a cell can lead to cancer, even in someone with no genetic predisposition. This is known as the ----of cancer, in which each "hit" is a mutation, and multiple hits are needed to cause the disease. Mutations that cause cancer typically occur in two types of genes that influence the cell cycle: Normal proto-oncogenes activate ---, but only in response to appropriate signals. When proto-oncogenes are mutated, they can become permanently turned on, stimulating cells to divide all the time. In this state, they are called oncogenes—literally, "---." In other words, oncogenes are proto-oncogenes that have mutated to become permanently activated. Her2, a gene frequently mutated in certain types of breast cancer, is an example of a proto-oncogene. Tumor suppressor genes make proteins that normally ---,----,----. Tumor suppressor genes cause cancer when they are inactivated by mutation. More than 50% of all cancers have a mutation in the p53 tumor suppressor gene, for example. Without a properly functioning p53 protein, cells cannot commit suicide in response to DNA damage, and mutations accumulate in cells as a result. The BRCA proteins are also tumor suppressors. If a proto-oncogene is mutated, it's as if the accelerator is stuck down and cell division keeps going; if a tumor suppressor gene is mutated, it's as if the brakes don't work and the cell division cannot be stopped (INFOGRAPHIC 10.5).

BRCA alleles additional, nonhereditary (that is, acquired) mutations multi-hit model proto-oncogenes and tumor suppressor genes. cell division genes that cause cancer pause cell division, repair damaged DNA, or initiate apoptosis

How does cancer develop, how is it treated, and how can people reduce their risk?

Cancer is a disease of unregulated cell division. As we saw in Chapter 9, cell division is an essential part of the growth and repair of tissues. Normally, cells divide only in response to appropriate growth signals. When cells no longer need to divide—for example, when a wound has healed or worn-out tissues have been replaced—these growth signals are turned off and cells take a break. Cancer cells, on the other hand, divide even in the absence of growth signals and without stopping. Cancer is cell division run amok. The good news is that studies have shown that diet and lifestyle changes can dramatically cut a woman's risk of getting cancer—just quitting smoking cuts the risk by 30%. The bad news is that prevention is not that simple for women with inherited predispositions to breast cancer—for this group, diet and lifestyle changes make less of a difference. That's because, as scientists have learned, a genetic mistake stacks the deck against them, creating biological conditions conducive to cancer development. What's more, even after receiving treatment for cancer, women with BRCA mutations are at risk of developing a new cancer. But these women do have options that can drastically reduce their risk of getting cancer and options for treating it if it occurs.

CHAPTER 10 SUMMARY

Cancer is uncontrolled cell division caused by mutations—changes in the nucleotide sequence of DNA. Cancer cells have lost the ability to regulate cell division and reproduce uncontrollably, in most cases eventually forming a tumor. Cell cycle checkpoints ensure accurate progression through the cell cycle; repair mechanisms at each checkpoint can fix mistakes that occur, such as improper base pairing or DNA damage. In the absence of proper checkpoint function, cells may fail to properly repair DNA mistakes, leading to mutations that are passed on to daughter cells. Mutations occur spontaneously during DNA replication. They can also be caused by environmental triggers such as tobacco, UV radiation, chemicals, and viruses, and by chemicals naturally produced by the body. Mutations in two types of genes, proto-oncogenes and tumor suppressors, cause most cancers. Multiple mutations must occur in the same cell for the cell to become cancerous. People with "hereditary" cancer inherit predispositions to the disease in the form of specific genetic mutations. These mutations are present in all body cells and can serve as the first genetic "hit." Women with BRCA mutations have a much higher risk of developing cancer, and at an earlier age, than women without these mutations. Alternate forms of the same gene, with different nucleotide sequences, are called alleles. Certain alleles are more common in ethnic groups that were at some point small in number and genetically isolated, their members often marrying within their own group. Cancer is often treated with a combination of surgery, chemotherapy, and radiation. New and promising cancer treatments include targeted therapy and immunotherapy. Women who test positive for BRCA mutations may consider prophylactic removal of the ovaries or breasts to prevent cancer developing in these organs.

CHAPTER 9 SUMMARY

Cell division is a fundamental feature of life, necessary for normal development, growth, maintenance, and repair of the body. The cell cycle is the sequence of steps that a cell undergoes in order to divide. During the cell cycle, one parent cell becomes two daughter cells. Stages of the cell cycle include interphase, when the cell's contents, including organelles and DNA, are replicated; mitosis, when the replicated chromosomes (in the form of sister chromatids) are pulled apart; and cytokinesis, when the cell physically divides into two daughter cells. Mitosis is a critical part of cell division and takes place in several phases, each of which is important to properly segregate chromosomes into daughter cells. The structure that aligns and segregates sister chromatids is the mitotic spindle; it is made up of microtubule-based fibers, which attach to centromeres and lengthen and shorten to push and pull the chromosomes. Stem cells are relatively unspecialized cells that can divide and differentiate into different cell types. Stem cells can be used therapeutically to engineer or regenerate tissues and organs. Making new tissues requires both cell division and cell differentiation. Cell differentiation is the process by which an unspecialized cell becomes a specialized cell with a unique function. All cells in the body have the same genome but express different genes. Such differential gene expression causes each cell type to produce different proteins and to have different functions. Regenerative medicine involves using stem cells to repair or regrow damaged tissues and organs.

A Scenario: Mother: Homozygous recessive for dwarfism (aa) Father: Homozygous dominant for dwarfism (AA) What is the likelihood these two people will have a child that is a dwarf?

Dwarf = AA or AaPossible Offspring 4:4 or 100% will have Aa or 100% The answer is: The likelihood that these two people will have a child that is a dwarf is 100%.

CHAPTER 12 SUMMARY

Humans have 23 pairs of chromosomes. One of these pairs is the sex chromosomes: XX in females and XY in males. It is the presence of the Y chromosome that determines maleness, and therefore it is fathers who determine the sex of a baby. Sex as a body phenotype is determined by genetics working in combination with hormones; variations in either genes or hormones can lead to intersex or cases of ambiguous genitalia. Disorders and other traits inherited on X chromosomes are called X-linked traits, and are more common in males than in females. Because the Y chromosome in a male does not have a homologous partner, it does not recombine during meiosis. The Y chromosome a son inherits from his father is essentially identical to the Y chromosome his father inherited from his father (the grandfather), a fact that can be used to establish paternity. Familial hypercholesterolemia is a trait that exhibits incomplete dominance, a form of inheritance in which heterozygotes have a phenotype intermediate between the two homozygotes. ABO blood type is an example of a codominant trait—both maternal and paternal alleles contribute equally and separately to the phenotype. Many traits are polygenic—that is, they are influenced by the additive effects of multiple genes. Polygenic traits often show a continuous, bell-shaped distribution in the population. Human height is an example. In many cases, a person's phenotype is determined by both genes and environmental influences; this type of inheritance is described as multifactorial. Depression and cardiovascular disease are examples of multifactorial illnesses. Some genetic disorders result from having a chromosome number that differs from the usual 46. Down syndrome, or trisomy 21, is caused by an extra copy of chromosome 21. Aneuploidy, having one or more extra or missing chromosomes, is the result of nondisjunction—when chromosomes fail to separate properly during meiosis, generating aneuploid gametes.

GONADS ANDROGENS ESTROGENS AUTOSOMES

Sex organs: ovaries in females, testes in males. A class of sex hormones, including testosterone, that are present in higher levels in men and cause male-associated traits like deep voice, growth of facial hair, and defined musculature. A class of sex hormones, including estradiol, that are higher in women than in men and support female sexual development and function. Paired chromosomes present in both males and females; all chromosomes except the X and Y chromosomes.

Some traits are not inherited in simple dominant or recessive inheritance patterns. What are some complex inheritance patterns?

Sex-linked traits—those influenced by genes on either the X or Y chromosome—have distinct patterns of inheritance compared with traits influenced by genes on the autosomes. In the latter case, males and females inherit the trait with equal probability. In the former case, males and females are affected differently. Traits such as DMD, hemophilia, and red-green color blindness that are inherited on X chromosomes are called X-linked traits

ANGIOGENESIS CHEMOTHERAPY RADIATION THERAPY TARGETED THERAPY .

The growth of new blood vessels. Treatment by toxic chemicals that kill cancer by interfering with cell division. The use of ionizing (high-energy) radiation to treat cancer. A cancer therapy that is specific for cancer cells and not harmful to normal cells

How do chromosomes determine sex, and how does sex influence the inheritance of certain traits?

Whether a fetus develops male or female gonads depends on the set of chromosomes it receives from its parents. Humans have 23 pairs of chromosomes; 22 pairs are autosomes and 1 pair are the sex chromosomes, X and Y. Females have two X chromosomes, while males have one X and one Y. Sons inherit their Y chromosome from their father and their X chromosome from their mother. Daughters inherit one X chromosome each from their mother and father. The Y chromosome contains a gene called SRY that signals testes to develop. (SRY stands for "sex-determining region on the Y chromosome.") The testes, in turn, produce masculinizing hormones such as testosterone that lead to the development of a male body. In the absence of a Y chromosome, a fetus will develop into a female. Thus, fathers determine the sex of a baby by providing either an X or a Y sex chromosome in the sperm that fertilizes a mother's egg

What is regenerative medicine, and what are specific approaches to repairing or replacing organs?

With regenerative medicine, scientists hope to coax cells to both divide and differentiate on cue—not only to produce enough cells to build an organ, but also to have them be the right sort of cells, capable of carrying out the unique functions of a particular tissue. Scientists are exploring several different approaches to regenerative medicine, although not all of them are equally far along. One approach uses drugs to stimulate stem cells in the body to grow and differentiate into the tissues that need repairing. In some ways, this approach represents the ultimate goal of regenerative medicine, but its use is still a long way off, mostly because scientists still have a lot to learn about stem cells

Why do people with "inherited" cancer often develop cancer at a relatively young age?

Women who, like Ahern, have a genetic predisposition to getting cancer are often said to have "hereditary" or "inherited" cancer. This does not mean that their cancer was passed from parent to child, the way that eye or hair color is. It means that they have inherited a genetic mutation, from one or both parents, that makes the development of cancer much more likely. In other words, the cancer itself is not inherited, but the risk of getting it is. A person who inherits a BRCA mutation starts life with at least one cancer-predisposing mutation, so he or she requires fewer additional mutations to develop cancer. Because it disrupts DNA repair, a single mutated BRCA allele is enough to increase the chances that additional mutations will occur in a cell; DNA damage will go unrepaired—or be repaired incorrectly—leading to a change in the nucleotide sequence of DNA. Daughter cells will accumulate mutations at a faster rate, which is why hereditary breast cancer often strikes women who are in their 30s and 40s—much younger than women who have no inherited predisposition to cancer. Typically, by the time a woman with an inherited predisposition develops breast cancer, her other (normal) copy of the BRCA gene will have been mutated as well.

Substances that are known to cause cancer, or increase its risk of forming, are called ----. Most carcinogens are also ===—physical or chemical agents that cause mutations in DNA. Not all mutagens originate outside the body. For example, some of the reactions that occur in the mitochondria during cellular respiration (see Chapter 6) produce DNA-damaging molecules called free radicals

carcinogens mutagens

What causes cells to "go rogue"? Cancer results when cells accumulate DNA sequence changes—mutations—that interfere with the orderly steps of the cell cycle. Mutations can happen in a variety of ways. Every time a cell replicates its DNA, for example, there is a small chance that it will make a mistake—insert the wrong nucleotide, for instance. Environmental insults, like smoking or a bad sunburn, can also damage DNA. Normally, such DNA damage is caught and repaired by the cell at a ---. Cells have a series of such checkpoints, which monitor each stage of the cell cycle and prevent progression through the cell cycle until previous stages have been successfully completed. At one checkpoint, for example, proteins scan DNA for damage or incorrect base pairing. If problems are detected, one of two things happens: either the cell ramps up ---, giving itself time to fix DNA mistakes, or, in the case of severe and irreparable damage, the checkpoints direct a cell to commit suicide in a process called --- Even with these checkpoint mechanisms, cells with mutations do occasionally manage to slip through the cell cycle and divide. This is especially likely if the mutations affect genes that code for proteins that function as checkpoints. Defective checkpoint proteins don't do their jobs, so additional mistakes continue to accumulate in these cells. When cells accumulate enough DNA damage to interfere with multiple checkpoints, the result is cancer. Cancer cells plow through the cell cycle unimpeded, divide uncontrollably, and in many cases eventually form a mass of cells called a ---

cell cycle checkpoint DNA repair mechanisms apoptosis tumor

Another important blood type marker is Rh factor, a protein found on the surface of red blood cells. The Rh factor is encoded by a gene found on ====Your Rh status, ===or---indicates the ---or---of the Rh factor protein on the surface of your red blood cells. The inheritance pattern for Rh factor involves dominant and recessive alleles: positive Rh factor alleles (Rh+) are dominant over negative Rh factor alleles (Rh-), which do not produce the protein. So if a person carries one positive and one negative allele, the positive allele will dominate and that person will have an Rh-positive phenotype. type O Rh-negative donors are known as universal donors because their blood can be transfused to people of any other blood type. Red blood cells from these donors lack the surface markers that the immune system recognizes as foreign and so will not trigger an immune response in a recipient. Because any person can receive O Rh-negative blood, O-negative donors are always in demand. Blood banks can fall short of O-negative blood during such disasters as earthquakes or hurricanes in which many people are hurt and require blood. People with type AB Rh-positive blood can receive any type of blood and are known as universal recipients A Mismatched Blood Transfusion Causes ---

chromosome 1. (+) or (-), presence or absence Immune Rejection

There are two common alleles of the serotonin transporter gene, which is located on ---: a short version and a long version. The long version contains about 44 extra-base pairs in the regulatory sequence of the gene that causes it to be transcribed into protein more efficiently. Previous research had shown that people with one or two copies of the short allele exhibit more intense ---and---reactions in response to fearful stimuli compared to people who are homozygous for the long allele. So the serotonin transporter gene seemed like a logical place to start to understand the individual differences in responses to stressful life events. The results were striking: clinical depression was diagnosed in 43% of participants who had two copies of the short allele and who had experienced four or more tumultuous events. By contrast, only 17% of participants who had two copies of the long allele and who had endured four or more stressful events had become depressed. Participants with two short alleles who experienced no stressful events fared pretty well, too—they were no more likely to become depressed than those with two long alleles. Clearly, it was the combination of ---and---that more than doubled the risk of depression The combination of hard knocks and short alleles more than doubled the risk of depression. Depression Can Result from a Combination of Genotype and Life Experiences In other words, mental illnesses exhibit ---inheritance. Multifactorial inheritance is a common pattern of inheritance. Diseases such as asthma, diabetes, and heart disease are all caused by a combination of several genes and their interaction with the environment.

chromosome 17 fear and anxiety hard knocks and short alleles multifactorial

Doctors have known for decades that breast cancer runs in certain families: a woman's chance of getting the disease is greatly increased if she has a sister or mother who has it. But it wasn't until the 1990s that researchers homed in on the reason: mutations in a particular region of ---are unusually common in these families. By the middle of the decade, scientists had isolated the specific mutated gene, which they called BRCA1, and determined its function. BRCA2 was not far behind In their normal form, the BRCA1 and BRCA2 proteins help to repair ----, specifically a type of damage called a ---. When these proteins are mutated, cells can no longer properly repair this type of damage. As a result, additional genetic mistakes—additional mutations—accumulate in these cells, eventually leading to cancer. Scientists estimate that inherited mutations like those in BRCA genes account for about 5%-10% of all cancers. The other 90%-95% of cancers are caused by ----(that is, acquired) mutations that occur during a person's lifetime.

chromosome 17 DNA damage double-strand break non-inherited

Though it takes up only a fraction of the total cell cycle, mitosis is in some ways the star of the whole performance. It's mitosis that ensures that each new daughter cell has the proper number of ====—no more, no less than, in humans, a complete set of 46. Each chromosome contains a unique set of genes that instruct cells how to function, and so getting the distribution right is critical. If any chromosome is left out of a daughter cell, all the genetic information contained in that chromosome will be missing, which could spell disaster for the cell. You can think of mitosis as a carefully choreographed dance of chromosomes. At the beginning of the dance, the replicated chromosomes are present in the nucleus as loosely gathered threads. To prevent the chromosomes from becoming entangled during the dance, they condense into tightly wrapped, rod-shaped structures that can move about the cell more easily. If you peered at the cell through a microscope at this point, you'd see that the two identical sister chromatids of a replicated chromosome are connected at a region called the centromere. As mitosis progresses, these linked sister chromatids move across the stage and line up along the midline of the cell, like dancers in formation The chromosomes do not get there by chance. Rather, they are pushed and pulled into this position by protein fibers of a structure called the ----. The mitotic spindle is formed when microtubules of the cell's cytoskeleton rearrange into this structure as the nuclear membrane dissolves. Microtubule spindle fibers extend from each end of the cell and snag the centromere region of the chromosomes, with one spindle fiber attaching to the centromere of each sister chromatid. As spindle fibers lengthen and shorten, the attached chromosomes are moved around the cell, much like marionettes on strings. Once aligned at the midpoint of the cell, the two sister chromatids of each replicated chromosome separate from each other and are pulled to opposite sides of the cell by the spindle fibers, which contract to reel the chromatids in. Each chromatid will eventually form one of two genetically identical chromosomes—one for each daughter cell

chromosomes mitotic spindle

Blood type AB is an example of ===, in which the contributions of both the maternal allele and the paternal allele in a heterozygous individual are displayed in the phenotype. Unlike incomplete dominance, in which heterozygotes have an intermediate phenotype, codominant alleles share the limelight: heterozygotes express both traits. Blood type alleles A and B are codominant, while O is ---to both A and B. Consequently, if you have blood type A, your genotype will be either AA homozygous or AO heterozygous. The same goes for blood type B: you will have a genotype of either BB or BO. People with type AB blood have an AB genotype and express both A and B markers on their cells

codominance recessive

Geneticists estimate that height is 60% to 80% genetic. This means that genes account for 60% to 80% of the difference in height you see from person to person. But there isn't one single gene that determines height, there are many (more than 400 at current count). This is why we see such a range of heights among us. , height is a trait that shows ---in the population. This is in contrast to the discrete, or discontinuous, traits we've encountered, in which individuals have one of only two or three possible phenotypes for a given trait—Mendel's round or wrinkled peas (see Milestone 4: Mendel's Garden), or ABO blood type, for example. Why does height show an unbroken range of phenotypes rather than discrete categories like tall or short? The main reason is that human height is a ---—one that is influenced by more than one gene. When multiple genes act together, their effects add up to produce a range of phenotypes. Another example of a polygenic trait is skin color. Even though 60% to 80% of the variation we see in height is due to genes, another 20% to 40% is due to ---factors such as nutrition. When both genes and environment work together to influence a given trait, the trait is described as ---. So height is both polygenic and multifactorial. Many polygenic traits, such as height and skin color, are influenced by both genes and the environment and thus may be considered multifactorial

continuous variation polygenic trait environmental multifactorial

To produce new cells by cell division, cells pass through a series of stages collectively known as the cell cycle During the cell cycle, one cell becomes two. A cell doesn't simply split in half, however. If it did, each resulting cell would be smaller than the original, and with each division, each cell would lose half its contents. So before a cell divides, it first makes a ---of its contents so that each new cell has the same amount of organelles, DNA, and cytoplasm as the original cell. This preparatory stage of the cell cycle, called ---, has separate subphases: G1 phase, when the cell grows larger and begins to produce more ---and organelles; synthesis phase (S), when ----is replicated and therefore chromosomes are duplicated forming linked sister chromatids; and G2 phase, during which the cell prepares to enter the ====phases. In a cell that takes approximately ----to divide, the interphase takes about ----to complete. Once the cell duplicates its contents, it enters the ---phases of the cell cycle: mitosis, when the ---of each replicated chromosome are evenly divided between the two daughter cells; and cytokinesis, when the two daughter cells ---. Together, mitosis and cytokinesis take about ---to complete. Once the cell is finished dividing, it may enter a resting phase of the cell cycle, called G0, during which the cell goes about business as usual

copy interphase cytoplasm DNA division 24 hours 22 hours division sister chromatids physically separate 2 hours

Though checkpoint mechanisms ensure that the vast majority of DNA replication mistakes are fixed, on average 1 uncorrected mistake occurs for every 10 billion DNA base pairs that are replicated. Moreover, our DNA is continually being bombarded by ----that can add to our mutation burden. Environmental insults from chemicals, ultraviolet light, radiation, and infectious agents like viruses can damage DNA, causing mutations. Exposure to ultraviolet light, for example, damages the DNA in our skin cells, causing mutations that can lead to skin cancer. Radiation from X-rays and other diagnostic imaging tests can damage DNA, increasing the risk for several types of cancer (although the benefits of the procedure usually outweigh the risks). And chronic infections of the hepatitis B or C virus can damage liver cells, causing mutations that can lead to liver cancer.

environmental insults

What's more, inherited mutations are the source of the genetic variation on which ---. Without mutation, there would be no evolution at all, and the great diversity of living creatures we see around us would not have been possible. When it comes to surviving and reproducing, mutations can be ---,---or---. Harmful and beneficial mutations will affect the fitness of an individual and may influence his or her ability to survive and reproduce, leading to evolution by natural selection

evolution acts harmful, neutral, or beneficial

What causes intersex? Some instances of intersex have ===causes. For example, if the Y chromosome has a mutation in the SRY gene, a baby is likely to have undeveloped gonads with external female genitalia, even though it carries an XY chromosome pair. Similarly, there are people with XX sex chromosomes who have male genitalia. In some cases, this is caused by a condition called ----. These individuals have one or more mutations in genes on autosomal chromosomes, leading to excessive production of androgens. These people have ovaries but may have genitals that appear more male than female. Some people have only one sex chromosome, while others have three. Every person must have at least one X chromosome (having none is fatal), but because of errors in chromosome segregation during ----, a variety of other X and Y combinations are possible: XXY men, women with only a single X chromosome, XXX females, and XYY males. In many of these cases, a person's physical traits and genitalia reveal that they do not have the usual makeup of sex chromosomes, but not always

genetic congenital adrenal hyperplasia meiosis

When someone needs a blood transfusion, the donated blood cannot come from just anyone. The transfused blood must be compatible in ways that are determined by --- The two most important genetic attributes are ===and===, both of which must be compatible between donor and recipient. Mixing incompatible blood leads to an immune reaction against the genetically mismatched cells, causing blood cells to clump together and ultimately form life-threatening ---. our ABO blood type indicates the presence or absence of ===on the surface of your red blood cells. For example, if you have type A blood, your cells display A markers, whereas if you are type B, your cells have B markers. If you have type O blood, then you lack both A and B markers. And if you have type AB blood, then you have both A and B markers.

genetics ABO blood type and Rhesus (Rh) factor blood clots specific markers

Sex hormones are produced by sex organs called ---—ovaries in females, testes in males. Sex hormones include androgens (from andros, Greek for "man"), such as testosterone, and estrogens (from the Greek oistros, meaning "frenzy" or "passion") such as estradiol. Both males and females produce androgens and estrogens, but in most cases males produce higher levels of androgens and females produce higher levels of estrogens. In a developing fetus, these hormones shape the development of both internal and external sexual anatomy.

gonads

Normally, cells divide only when they are signaled to do so by molecules called ---. This is generally a good thing since if cells divided without receiving the proper cues, there would be so many cells that a body could not maintain its structure. But this need for division signals becomes a liability when ---since scientists have to figure out what those signals are. For some cells—like nerve cells, liver cells, and pancreas cells—researchers are still looking for the right signals, and so these cells remain very difficult to grow outside the body

growth factors growing organs

Y-chromosome analysis. As the name implies, in this technique researchers examine the Y chromosome, which is very small and contains few genes. Sons inherit their Y chromosome from their fathers. These Y chromosomes are passed through generations, from fathers to sons, largely unchanged. That's because Y chromosomes have no ----with which to pair and exchange DNA during meiosis In other words, the Y chromosome rarely undergoes genetic ---. Consequently, the Y chromosome that a son inherits from his father is almost identical to the Y chromosome that his ====inherited from his father. Comparing DNA sequences on Y chromosomes, therefore, can reliably establish paternity

homologous partner chromosome recombination father

When heterozygotes have a phenotype that is intermediate between the two homozygotes, the inheritance pattern is called ----. Incomplete dominance is shown when one allele does not completely mask the presence of the other allele, and there is a measurable effect on the phenotype of having one versus two copies of a dominant allele. (This is in contrast to complete dominance, in which one allele masks the other and homozygotes and heterozygotes have indistinguishable phenotypes.) An example of incomplete dominance in humans is familial hypercholesterolemia (FH). This dangerous condition results from inherited mutations in the gene encoding the low-density lipoprotein (LDL) receptor, which helps remove harmful cholesterol from the blood Intermediate/ incomplete dominance; Definition -When both recipes are expressed at the same time but the resulting character or trait is an intermediate expression of both, because neither dominates over the other; Example- These characters are said to present an INCOMPLETE OR PARTIAL DOMINANCE, for instance if we cross-breed white flowers with red flowers, the descendants will have pink flowers. The pink flowers are the result of mixing up both pigments.

incomplete dominance

Mutations can take several different forms. A mutation can be a point mutation, a change in just ----. Depending on where that point mutation occurs, it may change the amino acid sequence of the protein, or it may not. Point mutations that change the amino acid sequence are called ---; those that do not change the sequence are called ----. In other cases, one or more DNA nucleotides may be inserted or deleted from genes, changing the reading frame of that gene—that is, changing the way the nucleotides are divided into the triplet letters of DNA codons. Whole blocks of DNA can be rearranged as a result of mutation. These kinds of rearrangements can include a segment of DNA that "flips" within its normal chromosomal location (this is called an ===), or segments of DNA that trade places between different chromosomes (===). Large inversions and translocations can fuse portions of different genes together, creating new proteins with novel activity Ultimately, the impact of a mutation on the function of the encoded protein depends on ---in the gene the mutation occurs and on the effect of this change on the ----of the protein. Some mutations have no effect on the amino acid sequence and therefore do not alter the function of the protein. In many cases where the sequence is changed, the new sequence alters the shape of the protein in a way that makes it ---. In other cases, the mutation changes the shape of the protein in a way that makes it ---. If the proteins encoded by these genes play roles in the cell cycle, the mutations and corresponding changes in protein activities may eventually lead to cancer. The most common mutations in BRCA genes are ---that hobble the function of the encoded proteins, making them ineffective at DNA repair Mutations that occur in --- these mutations are passed from cell to cell through ---, but not from parent to offspring, and so they are not ---. Occasionally, mutations will occur in a ---—an egg or a sperm cell. These mutations can be passed on to offspring through sexual reproduction (see Chapter 11). Mutations inherited via germ cells are present in every cell of the adult person's body. And if that person has children, their children can inherit those mutations, too. This is how BRCA mutations were introduced into the population.

one DNA nucleotide missense mutations silent mutations inversion translocations where amino acid sequence nonfunctional overly active deletions body cells mitosis inherited germ cell

Determining what pattern of inheritance a particular trait has is easy to do with plants or laboratory animals, where you can perform a carefully controlled genetic cross—as Mendel did with his peas (see Milestone 4: Mendel's Garden). With humans, it's not possible to conduct such crosses. Instead, scientists rely on a tool called a ----to determine a pattern of inheritance in humans. With the help of a pedigree that extends back several generations, scientists can determine whether a trait is inherited on ----or --- A Pedigree Analysis Can Help Determine a Sex-linked Pattern of Inheritance

pedigree autosomes sex chromosomes.

There are four stages of mitosis:

prophase, metaphase, anaphase and telophase. 1) Prophase: chromatin into chromosomes, the nuclear envelope break down, chromosomes attach to spindle fibres by their centromeres 2) Metaphase: chromosomes line up along the metaphase plate (centre of the cell) 3) Anaphase: sister chromatids are pulled to opposite poles of the cell 4) Telophase: nuclear envelope reforms, chromosomes unfold into chromatin, cytokinesis can begin The order of the stages of mitosis can be remembered using the mnemonic PMAT.

For scientists working to grow new organs, inspiration comes from an unlikely place: ---. These four-legged amphibians have a remarkable ability to regenerate body parts that have been injured or even severed.

salamanders

It usually takes more than a ----in a cell to cause cancer. In most cases, a cell will become cancerous only after it has acquired multiple mutations—multiple "hits"—in several genes that regulate the -----. The collection of mutated genes can include a combination of tumor suppressor genes that have lost their function and proto-oncogenes that have been activated to oncogenes. This is one reason cancer affects people more as they age: as cells accumulate mutations over time through exposure to carcinogens and repeated rounds of cell division, the chances increase that a cell will accumulate enough mutations to become cancerous. After one or two hits, a ----may form. Cells in a benign tumor divide more frequently than do cells in normal tissues, but they do not spread to other areas and so are usually much less dangerous. After several more mutations, a ----may result. Malignant tumors have the capacity to ---, their cells invading other tissues and spreading to other parts of the body. Cancer cells have other distinctive properties that set them apart and contribute to malignancy. Normal cells stop dividing once they come into contact with neighboring cells, a property called contact inhibition. As genetic mutations accumulate, cancerous cells usually lose this property. The result is a pile of cells growing on top of each other. Normal cells also usually require connections to the tissue to which they belong; this is called ----. Cancer cells typically lose this constraint as well, and so are enabled to detach and spread. Finally, cancer cells promote the growth of new blood vessels, or angiogenesis, to acquire oxygen and nutrients for growth

single mutation cell cycle or repair DNA damage benign tumor malignant tumor metastasize anchorage dependence

Where do these new cells come from? Many tissues in the body contain what are called ===—immature cells that can divide and give rise to cells of different types. When a stem cell divides, one of the daughter cells remains an ----, while the other one "---," developing into a more specialized cell. In this way, stem cells contribute to tissue repair but retain the capacity for further cell division in the future. The first stem cells to be discovered were those that produce all the various cells making up blood (these are called hematopoietic stem cells). Scientists have since discovered that many other tissues contain stem cells as well. Stem cells have been found in the brain, blood vessels, muscle, skin, teeth, heart, gut, liver, ovaries, and testes, for example. Stem cells also make up part of a developing embryo, where they give rise to a wide range of cell types. Stem cells found in adult tissues are sometimes called adult stem cells to distinguish them from the embryonic stem cells found in an embryo

stem cells immature stem cell grows up

Scientists are exploring several different approaches to regenerative medicine, although not all of them are equally far along cont: Another approach, somewhat further along, is to remove ---from the body, ---them to reproduce and differentiate, and then---- the cells into a patient with a damaged tissue or organ. This approach has been used in patients with damaged heart tissue following heart attacks and in those with macular degeneration of the eye—two cases where it has shown promise. The third approach is one that Atala has used to create new bladders, urethras, ears, and other organs: ====on a biodegradable scaffold outside the body, growing a new organ, then implanting it in a patient. He has also begun using cadaver-derived organs as the scaffold. These organs are washed of their cells, leaving only the protein (mostly collagen) matrix that imparts structure and shape to the organ. This matrix then serves as a scaffold for new cells from the patient's own body to grow on and in

stem cells stimulate re-implant seeding cells

Inherited mutations aren't always bad; they do more than cause cancer and other genetic diseases. In fact, inherited mutations are the source of all the interesting ---we see from individual to individual. Whether you have blue eyes or brown eyes, red or black hair, are musically inclined or athletic—all these traits reflect the influence of different variations of genes, each originally the result of mutation. Different versions of the same gene, produced through mutation, are called ---. Alleles are the basis of the ---that makes each of us unique (see Chapter 11). People with blue eyes, for example, have alleles for eye color that are different from the ones people with brown eyes have.

variations alleles genetic inheritance

How and why do cells divide?

why - Cell division is a normal part of the development, growth, maintenance, and repair of the body. In fact, cell division in our bodies begins long before we are born how - During embryonic development, a single fertilized egg cell divides, and its daughter cells divide again and again, eventually forming trillions of cells by the time a baby is born. During childhood, cell division helps us grow larger. As we age, our tissues continually discard old cells and generate new ones in their place. And when we cut or injure ourselves, cells in the area divide to heal the wound