Bio 302 Genetics Exam #3

Cancer stem cell

cancer cells (found within tumors or hematological cancers) that possess characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample.

Metastasis

cells break away from the original cancer tissue and move to other parts of the body, starting new tumors in new tissues

Translation takes place in the cell's __

cytoplasm

Proteins are made in the

cytoplasm, but are present in all parts of the cell

Explain the process by which steroids (e.g. testosterone or cortisol) can regulate gene expression by influencing the activity of a transcription factor. Hint: This will be discussed in class

different tissues respond to steroids in different ways: cells in genital tissue may be stimulated to grow faster, cells in the brain may be stimulated to be more electrically active, and endocrine cells may be stimulated to secrete more hormones. In other words, sex steroids modify the behavior of a tissue within the range of options available to that particular tissue. it should also be mentioned that steroid hormones can affect target cells by other means than binding to the "classic" steroid receptors that control gene expression. They can also affect cellular processes more directly by binding to receptors in the plasma membranes of cells; these receptors influence metabolic processes directly, without involving gene expression

The nitrogenous bases of DNA stores genetic information. True or false

True

The name of the enzyme that replicates DNA is

DNA polymerase

Heterochromatin

Dark, stained--tightly packed, inactive

DNA Replication happens in

S phase

Adenine is a:

**Purine: two ringed nitrogen base *Purine and base* vs. Pyramiding which are one ringed nitrogen bases

Oncogene

*Cause increased cell division* -If uncontrolled cellular division occurs, mutated cells will pass through the cell cycle more quickly, and will likely bypass cell checkpoints that would've corrected the error. -having mutation in just one of the two proto-oncogenes is enough to cause a change in cell growth and the formation of a tumor -can be caused by *single base-pair changes* that lead to a hyperactive form of the proto-oncogene, by a *gene amplification event* that results in many extra copies of the proto-oncogene within the genome and higher expression levels of that gene, or by a *mutation in the promoter region of the proto-oncogene* that leads to an increase in its expression.

Describe the two major information transfer processes involved in gene expression and state where each occurs in the cell.

*Nucleus: Transcription* regulation determines which genes are transcribed and determines availability of mRNA to ribosomes *Cytoplasm: Translation* regulation determines the rate at which proteins are made and the availability of the finished proteins

Frameshift mutation

*cause the insertion or deletion of bases in a DNA molecule *Mutational events in which a number of bases (other than multiples of three) are added to or removed from DNA, causing a shift in the codon reading frame* -change the number of nucleotide sin the gene and usually cause *large-scale changes* in the amino acid sequence of the protein -Most occur near the end of the gene which has a minimal impact on the function of the protein *Shifts the codons because of addition or deletion of amino acids*

Proto-oncogenes

*checkpoint genes*--Normal genes that start or maintain cell division and that may become cancer genes (oncogenes) by mutation -when porto-oncogenes and/or their proteins are inactivated, normal cells stop dividing. Mutant proto-oncogenes are often switched on permanently and cells receive constant signals to keep dividing and uncontrolled cell division results

Tumor supressor genes and how mutations in these can can lead to cancer

*checkpoint genes--Suppress cell division*--control the process of cell growth and apoptosis -if these genes are mutated or inactivated, this inhibition is removed and cells pass through the checkpoints and divide uncontrollably *mutation in tumor suppressors will increase cell division*

How does 6 feet of DNA fit into the tiny nucleus in each of our cells?

-Nucleosome (combined tight loop of DNA and protein) is formed when 9 histone proteins subunits attach to DNA molecule -Multiple nucleosomes coil together and stack on top of each other to form chromatin -Chromatin is then looped and further packaged using other proteins -DNA is tightly packed into chromosomes

What are some of the social and ethical questions surrounding the use of these technologies?

-Is it ethical to make a shorter than normal child taller using biotechnology so he/she can have an advantage in sports? -Do consumers have a right to know what is in their food and should it be required to label GMOs in food? -what should be done with information that is found regarding major diseases (that may not even develop until decades later) and how can we protect access to the results of genetic testing? -Should we test for serious or fatal disorders for which there is no treatments? -It is our duty as citizens to become informed about these issues and to participate in formulating policy about the use of this technology

Why might the use of transgenic plants be more beneficial instead of animals?

-Lower costs -plants can be gown in large disposable plastic bags -can perform post translational modifications often required to make human proteins fully active -now finding higher yields of transgenic protein

The genetic material has to store information and be able to express it.What is the relationship among DNA, RNA, proteins, and phenotype?

-*DNA* is the genetic code that stores instructions for making a protein by having different combinations of base pairs -*mRNA* is involved in reading the DNA in a process known as *transcription*. It reads DNA by base pairing ATCG to their base complements in DNA. It is then processed by *ribosomes*, structures inside the cell, which produces proteins. Ribosomes read mRNA by attaching a complementary *tRNA*, which contains the the amino acids in a process known as *translation*. The amino acids on tRNA will bind to each other in order as the ribosomes read the mRNA. Similarly, after it is done reading mRNA, the chain of amino acids can be a functional *protein* or a polypeptide, which binds with other polypeptides to make a protein. -Proteins are responsible for the *phenotype*. For example, people with sickle cell anemia will produce a mis-shaped hemoglobin enzyme, resulting in sickle cell shaped red blood cells.

Why do genes have different mutation rates? i.e. why do some regions of DNA seem to be more susceptible to mutation than other regions of DNA?

-*Larger genes* have higher mutation rates (bigger target) -*Nucleotide sequence*: presence of nucleotide repeats are associated with higher mutation rates -*Spontaneous chemical changes*: C/G pairs are more likely to mutate than A/T pairs

Define replication, transcription, and translation. In what part of the cell does each occur?

-*Replication*: DNA strand is separated and replicating proteins such as DNA polymerase make complementary base pairs to form a copy of the original strand of DNA: takes place in the *nucleus of the cell or mitochondria* -*Transcription*: Transfer of genetic information from the base sequence of DNA to the base sequence of RNA, mediated by RNA synthesis--occurs in the *nucleus or mitochondria* -*Translation*: mRNA is processed by ribosomes which are read by tRNA--creates a protein: in *process occurs in the ribosomes in the cytoplasm*

Why do we say cancer is genetic?

-A predisposition to more than 50 forms of cancer are inherited to one degree or another -Most chemicals that cause cancer are also mutagens -some viruses carry genes that promote cancer -specific chromosomal changes are found in certain cancers (translocation, swapping information) -Mutations are the ultimate cause of cancer

In analyzing base composition of a DNA sample, a student loses the information on prymidine content. The purine content is A=27% and G=23%. Using Chargaff's rule, reconstruct the missing data and list the base composition of the DNA sample.

-Adenine=27% binds with Thymine=27% -Guanine=23% binds with Cytosine=23% -Amount of A is equal to amount of T -Amount of G is equal to amount of C

Different bases for DNA and RNA

-DNA has Thymine -RNA has Uracile Both have: Cytosine, Adenine, Guanine

Why would crops be genetically modified? Be able to give two examples of how this technology can improve crops.

-Dramatically increases the yield and nutritional value of crop plants -reduced production costs 1. Resistance to insects or herbicides 2. Enhances nutritional value of foods (such as enhancing vitamin D or reducing vitamin A, increasing levels of fatty acids, antioxidants, and minerals)

How is heterochromatin different from euchromatin? Which form would you expect to see during metaphase of mitosis? Why?Which form would you expect to see during anaphase? Why?

-Heterochromatin: densely/tightly packed around histone proteins- -remains highly condensed even in interphase -transcriptionally inactive -Euchromatin: loosely packed around histone proteins- seen during metaphase of mitosis because it can be transcribed--decondenses during interphase -only condenses during mitosis -transcription can occur

Estrogen estradiol

-Important transcription factor (with testosterone) elevated levels of estradiol cause "man boobs"--combination of estradiol and testosterone causes shrunken testicles and their libido remains elevated and can experience erectile malfunctions -sex steroid

How does DNA differ from RNA with respect to the number of chains, bases used, and sugar used?

-Number of chains: DNA contains two double stranded chains while RNA only contains one single strand. -Bases: DNA contains A, T, C, G, while RNA contains A, U, C, G. Sugar used: DNA contains deoxyribose sugar while RNA uses ribose sugar

Indicate in which category, transcription or translation, each of the following functions belongs: RNA polymerase, ribosomes, nucleotides, tRNA, pre-mRNA, DNA, anticodon, amino acids

-RNA polymerase: transcription -ribosomes: translation -nucleotides: transcription (monomers that make pre-mRNA) -tRNA: translation -pre-mRNA: transcription -DNA: transcription -Anticodon: translation (mRNA base pairing codons with anticodons) -amino acids: translation

Distinguish between a somatic and a germline mutation. Which one can be passed on to the next generation?

-Somatic mutations: occur in the cells of body that do not form gametes (liver, muscles, kidney,, etc). I fa mutation occurs in somatic cells, it will be passed on to all daughter cells by mitosis, but the mutation cannot be transmitted to future generations. -Germline mutations: occurs in cells that produce gametes. *passed to offspring*

How does the use of biotechnology improve human health? Be able to give two examples of how this technology is an improvement over past experiences.

-Using transgenic animal and plant cells to making human protein produces benefits to human health -Hemophillia: used to use blood to help hemophiliacs receive a blood clotting protein that they lacked but now the process does not use blood or blood cells due to the high HIV/AIDS issue that occurred during donations. -Pompe disease: autosomal recessive disorder that weakens and disables heart and muscle function caused by mutations in the enzyme that breaks down glycogen to make it available as an energy source for cells. Enzyme replacement therapy is used and affected individuals can receive doses of GAA produced by biotechnology. It was originally manufactured by transferring the human GAA gene into fertilized rabbit eggs. Continued advancements in biotechnology may provide safe and effective long-term treatment for this disease. *several other disorders are treated with enzyme replacement therapy

Loss of heterozygosity

-a gross chromosomal event that results in loss of the entire gene and the surrounding chromosomal region. *the normal allele is lost in the cancer cell* -In a cell, the loss of normal function in one allele of a gene where the other allele is already inactivated by mutation

What are microRNAs and how do they regulate gene expression?

-cellular RNA fragment prevents the production of a particular protein by binding to and destroying the messenger RNA that would have produced the protein. -Derived from transcribed single-stranded RNA that folds back upon itself, forming double-stranded regions in the molecule -Remaining single-stranded regions are removed by an enzyme (Dicer), creating a double-stranded RNA. -Other proteins attach to this RNA and degrade one of the two strands, leaving a small single-stranded RNA of 21 to 22 nucleotides bound to the proteins -microRNA/protein complex binds to all mRNAs with a complementary sequence, cleaving the mRNA or blocking ribosomes from loading onto the mRNA In either event, the mRNA is not translated

cancer cells are

-less specialized than normal cells -able to ignore signals that tell them to stop dividing -influence normal cells, blood, tissue around them to help feed the tumor (microenvironment) -hide from immune system

Testosterone

-testosterone can only bind to genes after they have first bound to the proper receptors and acts as a transcription factor only in those cells with androgen receptors -unnaturally high levels of testosterone cause shutdown of testosterone production and reduction in androgen receptors

PCR Process condensed:

1. A solution of DNA is heated to 90-100 degrees C shortly to break hydrogen bonds between two polynucleotide strands, producing two single-stranded molecules that serve as templates 2. DNA solution is rapidly cooled to about 50 degree sC and primers for DNA replication bind to complementary regions on the single-stranded DNA fragments, marking the boundaries of the region to be copied. 3. After the primers are bound to the template strands, the enzyme Taq polymerase synthesizes a complementary DNA strand beginning at the primers. -These three steps are then repeated by heating the mixure and converting double-stranded DNA into single strands, each of which will serve as template in another round of synthesis. After each round, there is a 2^n increase in amount of double-stranded DNA

PCR process:

1. PCR starts with fragment of double-stranded DNA 2. DNA is heated (90-100 degrees) to unwind it. The single strands become templates. 3. The reaction mixture contains primers designed to base-pair with complementary sequences at the end of the DNA to be copied -Primers mark boundaries of region to be copied 4. Mixture is cooled. Lowering the temperature promotes base-pairing between primers and the DNA strands to be copied 5. DNA polymerases recognize the primers and assemble complementary sequences to make new strands. This doubles the number of identical DNA fragments 6. Mixture is heated again. Raising temperature makes all double-stranded DNA fragments unwind. 7. Mixture is cooled. Lower temp. promotes base-pairing between more primers added to the mixture and the single strands. 8. DNA polymerase again doubles the number of identical fragments. Repeating the sequence of reactions doubles the number of DNA fragments each time. Billions of fragments are rapidly synthesized, as in the rows of PCR systems below that are copying human DNA

The genetic changes that contribute to cancer tend to affect three main types of genes:

1. Proto-ocogenes 2. DNA repair genes 3. Tumor suppressor genes: produce proteins that keep cell cycle under control

What are the three modifications made to pre-RNA molecules before they become mature mRNAs, and what is the function of each modification?

1. Removal of introns to generate a coding sequence that can make an amino acid chain; as introns are removed, the exons are spliced together to form mature mRNA molecules 2. A nucleotide cap is added at the 5' end for ribosome binding 3. A poly-A tail (consists of 30 to 100 A nucleotides) is added at the 3' end for mRNA stability

Some concerns of GMOs

1. Transfer of herbicide resistance or insect resistance from crop plants to weeds and wild plants 2. loss of biodiversity caused by transgenic plants hybridizing with wild varieties of the same species 3. possible deleterious impacts on ecosystem

Cancer is characterized by what two main properties?

1. Uncontrolled cell division 2. Metastasis: ability of these cells to spread to other sites in the body

The number of different proteins a cell can produce is often much larger than the number of genes in that cell. (true or false)

True

You are running a PCR to generate copies of a fragment of the cystic fibrosis gene. Beginning with two copies at the start, how much of an amplification of this fragment will be present after six cycles in the PCR machine?

2^6=64

Polynucleotide chains have a 5' and 3' end. Which groups are found at each of these ends?

3' OH, 5' Phosphates -The 3' of the DNA is at the bottom an contains an -OH. The 5' end of the DNA shows a connection to a phosphate

The complementary sequence of 5'-ACGTC-3' would be:

3'-TGCAG-5'

The variability among people in sensitivity to environmental carcinogens is partly genetic.

True

Nucleosomes

A bead-like structure composed of histone wrapped with DNA

Dedifferentiation

A cellular process in which a differentiated cell loses its special form or function, or reverts to an earlier developmental stage

Protein

A class of cellular macromolecules composed of amino acid monomers linked together and folded into a 3-d shape

Stop codon

A codon in mRNA that signals the end of translation -UAA, UAG, and UGA are stop codons

Start codons

A codon present in mRNA that signals the location for translation to begin. The codon AUG functions as a start codon and codes for the amino acid methionine.

Anticodon

A group of 3 nucleotides in a tRNA molecule that pairs with a complementary sequence (known as a codon) in an mRNA molecule

Epimutation

A heritable change in gene activity that is *not associated with a DNA mutation but rather with gain or loss of DNA methylation or other heritable modifications of chromatin* *nonmutation-caused alterations*

What is a histone? How does it interact with DNA? What epigenetic modifications happen to histones that can cause them to "loosen their grip" on DNA? How might this affect gene expression?

A histone is a protein that DNA wraps around to compact it. Remodeling complexes (proteins) can loosen the binding between the histones and DNA, allowing for access to promoters. The process is called Chromatin remodeling. Whether the promoter is exposed or not will determine if the gene is expressed. Another way histones can loosen their grip is with lysine acetylation which increases gene expression.

Which of the following could result in the most serious type of mutation?

A nucleotide deletion in an exon

Negative feedback loop

A process in which a change from the normal range of function elicits a response that opposes or resists that change. 1. You have a stimulus, in which a change occurs. 2. You have a sensor, or the change is detected. 3. There's a control, which is just a response to the change 4. There's an effector, or the effect of the response.

Mediator protein

A protein complex that enables the RNA polymerase II-general RNA polymerase II transcription factor complex to react to transcriptional activator proteins; also enhances the level of basal transcription

Transcription factor

A regulatory protein that binds to DNA and affects transcription of specific genes

Epithelial cell mutations are the cause of most cancers (T/F)

True--lines ducts

Why do scientists think some children of Holocaust survivors have stress disorders?

A simple environmental event can affect the way genes work. Stress effects can be transmitted to children from their mother as a stressful event throws a switch on a gene which is then inherited by the children of the affected mother. Children of holocaust survivors have abnormal stress/cortisol levels because of the genes that were passed on to them by their mother.

In a missense mutation:

A single amino acid is altered

Messenger RNA (mRNA)

A single-stranded complementary copy of the amino acid coding nucleotide sequence of a gene

Transfer RNA (tRNA)

A small rNA molecule that contains a binding site for a specific type of amino acid and has a three-base segment known as an anitocodon that recognized a specific base sequence in messenger RNA

Antiparallel

A term applied to two molecules that are side by side but run in opposite directions. The two strands of DNA are antiparallel. The head of one strand is always laid against the tail of the other strand of DNA. -5'- ACGTT - 3' ---> 5'- AACGT - 3' = reverse complement

The start codon in translation is __

AUG-- 1. Encodes information for the amino acids methionine 2. It is always the first codon in the RNA

When proteins malfunction,

Altered phenotypes--genetic disorders

Compound heterozygote

An organism that has two recessive alleles for the same gene, but with those two alleles being different from each other -ex: both alleles might be mutated but at different locations

Covalent bond

Atoms in molecules held together by chemical links--A pair of electrons shared between two atoms

The steps in polymerase Chain reaction are:

Breaking down hydrogen bonds, annealing (heat and allow to cool slowly) primers, and synthesizing using DNA polymerase

In what direction does RNA polymerase build RNA? How does RNA polymerase know where to start? How does it know where to stop?

Builds the RNA in a 5' to 3' direction by moving 3' to 5' on the DNA sequence RNA Polymerase is attracted to a promoter (located on the control panel of the DNA) Start: In a stage called initiation, RNA polymerase (an enzyme) and several regulatory proteins bind to a specific nucleotide sequence (called a promoter) that marks the beginning of a gene Stop: When the RNA polymerase reaches the termination sequence (3' end), it stops adding nucleotides to the pre-mRNA and falls off the DNA template strand; the pre-mRNA molecule is released and the DNA strands re-form a double helix

Telomeres

Cancer cells rebuild the telomeres which helps them evade the mechanism that keeps them from dividing further

What is meant by "No one ever inherits cancer; what's inherited is the predisposition to certain sorts of cancers?" and "Just because you don't have a family history doesn't mean you won't get cancer"?

Cancer itself isn't heritable, however you can inherit genetic predispositions that make it more likely for you to develop cancer. Certain genes may cause a higher risk, and can cause cancer when combined with environmental agents. - A predisposition to more than 50 forms of cancer is inherited to one degree or another. -Environmental factors (such as chemicals, toxins, sunlight, smoking, etc.) can cause cancer -Mutations are the number one cause of cancer, and can occur throughout one's life when exposed to mutagens or as age increases.

Mutational hotspot

DNA sequences of high susceptibility to mutation due to some inherent instability, tendency toward unequal crossing over, or chemical predisposition to single nucleotide substitutions; region where mutations are observed with greater frequency

Intron

DNA sequences present in some genes that are transcribed but are removed during processing and therefore are not present in mature mRNA -Inexpressed sequence

___ proteins help fold the polypeptide chain after it has been translated

Chaperone

Chromatin

Complex of DNA, histones, and other proteins that form chromosomes

Translation

Conversion of information encoded in the nucleotide sequence of an mRNA molecule into the linear sequence of amino acids in a protein

___ carries genetic information

DNA

Which one of the following correctly describes the direction of transcription?

DNA is read 3' to 5' and RNA is synthesized 5' to 3'

Tight packaging

DNA packaging is a highly effective mechanism to make sure that most genes are off most of the time because it prevents transcription from occurring by preventing transcription factors from getting access to the genes. DNA is an enormous molecule, and the only way it can be scrunched down small enough to fit into your cell's nuclei is by being tightly wound round and round itself in supercoils. First, the DNA is wrapped around special proteins called histones. Then, the DNA and the histones, which together look a bit like beads on a string, are wrapped around and around themselves to form the dense DNA known as chromatin. When DNA is wrapped up this way, it can't be transcribed, because transcription factors can't bind to the DNA to find the template strand and copy it. This is the heart of epigenetics

How does DNA replication occur in a precise manner to ensure that identical genetic information is put into the new chromatid?

DNA polymerase is responsible for DNA replication occurring in a precise manner. And checkpoints are to ensure that each cell has identical information. But DNA replication doesn't always occur in a precise manner. DNA will sometimes add a mismatched base but detects the mistake and corrects it. Because purines and pyrimidines have to be paired with one another, DNA polymerase can detect when the shape of the double helix is off

How do cells sense and fix mutations?

DNA polymerase, the enzyme involved in replication, corrects many errors that lead to mutations. It has a proofreading function -If incorrect nucleotide is inserted, the enzyme can detect the error and reverse direction, move backwards and remove nucleotides until the incorrect nucleotide is eliminated

Exon

DNA sequences that are transcribed, joined to other exons during mRNA pressing, and translated into the amino acid sequence of a protein -expressed sequence

DNA is replicated during the __ stage of the eukaryotic cell cycle

DNA synthesis

DNA is replicated during the ___ stage of the eukaryotic cell cycle

DNA synthesis

Histones

DNA-binding proteins that help compact and fold DNA into chromosomes -Play important role in chromosomal structure and gene regulation -Major class of proteins in chromatin

Differences between RNA and DNA

DNA: -Stores RNA and protein encoding info -carries genetic information to cytoplasm to make proteins -replicates itself -transfers information to daughter cells -Double stranded -VERY stable -Deoxyribose as the sugar RNA: -Transfers genetic information from nucleus to cytoplasm -synthesizes proteins -component of ribosomes -Single stranded -NOT stable -Ribose as the sugar

Different sugars for DNA and RNA

DNA: Deoxyribose as sugar RNA: Ribose as sugar

DNA

Deoxyribonucleic acid --made of nucleotides *Primary carrier of genetic information*

RNA is ribonucleic acid, and DNA is deoxyribonucleic acid. What exactly is deoxygenated about DNA?

Deoxyribose sugar is missing an oxygen on carbon 2, while ribose sugar has an oxygen on carbon 2

Carcinogen

Environmental factors known to increase the risk of cancer

RNA Polymerase

Enzyme that copies the gene during transcription

For trinucleotide repeats, increasing size of repeat leads to

Earlier onset of disease in the next generation

Complementary base pairs

Either of the nucleotide bases linked by a hydrogen bond on opposite strands of DNA or double-stranded RNA: -GUANINE is the complementary base of CYTOSINE -ADENINE is the complementary base of THYMINE in DNA -ADENINE is complementary base of URACIL in RNA.

Epigenetics

Epigenetic regulation of gene expressions occurs when different cells have the same DNA blueprint but carrying varied molecular modifications which can be transmitted from mother cell to daughter cell during cell division. The modifications don't change the essential nature of the A C G and T alphabet of our genetic script. mRNA has the exact same sequence controlled by the base-pairng rules. *Epigenetic modifications don't change what a gene codes for; they change how well a gene is expressed*

Mutated oncogenes are called proto-oncogenes

False--proto-oncogenes are the wild type and oncogenes are the mutation

DNA methylation increases gene transcription (T/F)

False--turns off. High methylation levels generally result in lower expression levels for a given gene

Angiogenesis is the process that spreads cancer throughout the body (T/F)

False: supplies blood to tumors--mechanism used FOR metastasis

Describe what is meant by "alternative splicing" and give an example. How does alternative splicing affect protein structure?

Exons can be retained or removed during splicing, allowing mature mRNAs to contain different combinations of exons. It allows one gene to encode information for several different forms of protein. (occurs in more than 95% of human genes) Figure 9.5 Example: α-tropomyosin Smooth-muscle mRNA or Striated-muscle mRNA

Chromosomes in the euchromatin configuration are closed off from gene expression (T/F)

False

Micro RNAs are a mechanism for up regulating translation of certain genes (T/F)

False

The 3' end of DNA or RNA ends with a phosphate group.

False--It ends with a hydroxyl group

DNA polymerase adds nucleotides to the 5' end of the DNA molecule (T/F)

False--adds it to the 3' end

Fragile-X syndrome is an example of a genetic condition caused by a frameshift mutation. (T/F)

False--caused by an allelic expansion or trinucleotide repeats

BRCA1 and BRCA2 are genes that encode tumor suppressor proteins

False--encode DNA repair

Chromosomes in euchromatin configuration are closed off from gene expression (T/F)

False--loosely wound, therefore, open to gene expression

Which of the mutations would be most damaging and which would have no effect?

Frameshift would be most damaging -silent is least damaging because the same protein is encoded even with the mutation

In what part of the cell cycle is expression of BRCA1 and BRCA2 genes highest?

G1/S transition

If a coding sequence in DNA read CAT, what would the anticodon of the associated tRNA read?

GUA

Silencer DNA

Gene sequences that hook up with repressor genes to slow or stop transcription. Work to keep DNA tightly packaged and unavailable for transcription Both silencers and enhancers are often far away from the genes they control

Process of transcription: (needs to be completed)

Group of enzymes (holoenzyme complex) binds to promoter sequence of DNA. Promoter sequences are part of the genes they control and are found a few bases away.

Sugar-phosphate backbone

Groups that are on outside of the molecule and form a backbone of the change (while bases are inside)

In which type of cells would you expect steroids to be able to behave as transcription factors to turn on genes? What is different about these cells as compared to cells that do not respond to steroids?

Hair cells, skin cells, red blood cells, sex cells. Each cell type in the body has its own control mechanisms that determine which genes, out of the entire suite of genes that possess a steroid response element, are able to respond to the presence of the steroid. In part, these mechanisms involve yet another class of molecules known as coactivators that regulate the interaction between steroid receptors and response elements

Mutations

Heritable changes in the nucleotide sequence in DNA--results in changes in the structure and function of the proteins produced -Effects can be detrimental, beneficial, or neutral -Important role in evolution

__ proteins help to condense DNA before meiosis or mitosis

Histone

____ proteins help to condense DNA befor meiosis or mitosis

Histone

Nucleosome

Histones and DNA

What epigenetic modifications make histones hang on more tightly to DNA? How might this affect gene expression?

Histones hang on tightly to DNA because they are positively charged and DNA has a negative charge. If the DNA is wrapped tightly, the promoter cannot be accessed and the gene can't be expressed. Methylation (adding methyl group to cytosine bases) turns gene off, preventing expression as well.

What are some of the products made of recombinant DNA technology?

Human Growth Hormone (Dwarfism) , Human insulin (diabetes), Erythropoetin (Increases the oxygen carrying capacity of blood), enzyme replacement therapy (GAA for Pompe disease)

DNA contains many hydrogen bonds. Are hydrogen bonds stronger or weaker than covalent bonds? What are the consequences of this difference in strength?

Hydrogen bonds are caused by the partial charge between hydrogen and nitrogen of DNA and are responsible for two strands of DNA being stuck together. Covalent bonds are caused by the sharing of electrons and stabilize a structure, thus, covalent bonds are MUCH STRONGER than hydrogen bonds. Covalent bonds are responsible for the strand structure of DNA and the compounds within it. As a result, when heat is applied to DNA, hydrogen bonds break, causing the double stranded DNA to separate into single strands of DNA, but the covalent bonds are unbroken.

Androgen

Important transcription factors (testosterone and estrogen) -testosterone can only bind to genes after they have first bound to the proper receptors and acts as a transcription factor only in those cells with androgen receptors

Why is DNA synthesis considered to be semi-conservative?

In DNA replication, the 2 polynucleotide strands coil, and each is a template for synthesizing a new strand. A replicated DNA molecule contains one new strand and one old strand.

What is the function of DNA polymerase?

It adds DNA nucleotides to a replicating DNA strand

Which one of the following statements about genomic imprinting is FALSE?

It can occur in any gene

Which one of the following statements about genomic imprinting is FALSE?

It can occur in any gene (false) TRUE: a. It is considered an "epigenetic" change. b. It takes place during gamete formation or early embryonic development. c. It affects the expression of a gene, not the gene itself. d. The DNA changes involved are reversible.

Which of the following statements is not true about DNA replication?

It occurs during M phase: TRUE: -makes a sister chromatid -denatures DNA strands -occurs semiconservatively -follows base-pairing rules

Scientists were shocked when they found out that the 3 billion base pairs in the human genome only encoded about 21,000 protein-coding genes. Most of our DNA does not code for proteins. What does it do?

It turns out that many non-coding RNAs exist — that is, RNAs that don't code for proteins but play important roles in how genes are expressed

Which of the following statements is correct concerning the current regulation of genetically modified foods by the FDA?

Labeling of GMOs foods is not required

Euchromatin

Light, unravelled--loosely packed, active

Epigenetic changes that can lead to cancer development involve changes in the patterns of

Methylation, acetylation, etc.

Semiconservative:

Model of DNA replication that provides each daughter molecule with one old strand and one newly synthesized strand. DNA replicates in this fashion -One old strand is conserved in each new molecule, and one new strand is synthesized

Induced mutations

Mutations caused by exposure to environmental factors such as radiation or chemicals -chromosomal rearrangements, aneupoloidy, and issues in replication/transcription but all caused by mutagens

Do mutations in DNA alter proteins all the time?

Mutations in DNA are changes in the base of the gene. However, *not all mutations affect the protein product*. For example: Cysteine is coded by UGC and UGU. if the gene's mRNA originally has UC but a mutation changes the last C to a U, it would not affect the protein product.

Spontaneous mutation

Mutations that are caused spontaneously as a result of errors in DNA replication or transcription (DNA synthesis, transcription) -chromosomal rearrangements -aneuploidy

Missense mutation

Mutations that cause the substitution of one amino acid for another in a protein--can have affect on phenotype and cause genetic disorders but most do not have any phenotypic consequences -CAG-->GAG may cause abnormal hemoglobin like sickle cell anemia, while other substitutions will not have affect -Ex: sickle cell anemia *One amino acid for another*

Sense mutation

Mutations that change a termination codon into one that codes for an amino acid. Such mutations produce *elongated proteins* -Replacing a stop codon with a glycine codon will cause the insertion of 30 additional amino acids. *stop codon-->amino acid*

Nonsense Mutations

Mutations that change an amino acid specifying a codon to one of the three termination codons *shortens the product* -has little or not effect on the function of molecule, however other nucleotide substitutions can produce more drastic changes in polypeptide length and have more serious phenotypic effects. *Amino acid--> Stop codon*

Nucleotide substitution

Mutations that involve replace of one or more nucleotides in a DNA molecule with other nucleotides-- can involve substitutions, insertions, or deletions of one or more nucleotides in a DNA molecule. (usually involve only one or a small number of nucleotides)

Is an entire chromosome made into an mRNA during transcription?

No. Portions of the chromosomes are read, which code for genes. The primary transcript formed after transcription undergoes splicing. The sequence that are read do not code for proteins.

The basic building blocks of nucleic acids are:

Nucleotides: compounds that include a phosphate group, a ribose sugar, and a nitrogenous base

Amino acid

One of the 20 subunits of proteins. Each contains an amino group, a carboxyl group, and an R group -Twenty different types of amino acids re used to make proteins

Explain why chromosomal rearrangements like translocations can create cancer-causing genes, and describe one specific example.

One of the best-established links between cancer and chromosomal aberration is a translocation between chromosome 9 and chromosome 22 in chronic myelogenous leukemia. (Originally called Philadelphia chromosome) (LOOK AT TABLE 12.6) the C-ABL gene on chromosome 9 is combined with part of the BCR gene on chromosome 22 to form a hybrid gene. The normal BCR allele encodes a protein that switches other proteins on or off by adding phosphate groups to them. BCR target proteins control gene expression and cell growth. Hybrid gene encodes a unique protein that constantly signals the white blood cell to divide, even in the absence of external signals.

Insulin

One of the first drugs to be made by biotechnology to help with diabetes and regulates the amount of glucose in the blood

Anticipation

Onset of a genetic disorder at earlier ages and with increasing severity in successive generations--related to trinucleotide repeat expansion

DNA Profile and two examples of how they are used

Patterns of STR allele frequencies used to identify individuals used in: 1. criminal cases 2. paternity tests 3. studying human evolution 4. tracing ancient migrations 5. monitoring contamination of food by microorganisms -identify bodies and body parts of famous people whose graves have been moved several times

What are some potential ethical, legal, or social implications with respect to stress, epigenetics, and public health, specifically mental health?

People who suffer from mental illness are stigmatized in our society today. There are some who believe that mental illness occurs in individuals because of "bad choices" that person makes, which causes them to suffer from their own behavior which triggers a mental illness. Epigenetics, however, shows us that mental illness is very much related to genetics and that mental illness can be passed down through a number of generations before it is seen again in a current generation. Such genetic findings can help to validate the severity of mental illnesses and help those who suffer to be treated in a way that works for them.

Telomeres are shortened after each round of ___

Replication

Hypothalamic pituitary adrenal axis (HPA Axis)

Population of neurons in the hypothalamus produces cortisol which stimulates adrenal gland to release glucocorticoid stress hormones including cortisol -regulates stress response. releases CRH

What is the relationship between maternal stress and the health of the newborn baby? What role does the steroid hormone cortisol play?

Pregnant rats that were injected with stress hormones had children with altered stress responses and showed symptoms of behavior that was similar to that of the parents. Rats that were never exposed to the stress hormone also had abnormal stress responses generations later. A person produces cortisol—a hormone that helps a person respond to stress—during a traumatic or stressful event. Low levels of cortisol creates difficulty in dealing with stress as well as being more easily prone to PTSD. Women who are pregnant at the time of a stressful event (such as 9/11) have children with abnormal cortisol/stress levels because their child has been exposed to such factors during development which is considered to be an epigenetic effect.

mRNA splicing

Process that removes introns from pre-mRNAs and joins exons together. -allows genes to be expressed in new ways--one gene can code for more than one protein x -Alternative splicing: exons can be retained or removed during splicing, allowing mRNAs to contain different combinations of eons. Alternative splicing allows one gene to encode information of several different forms of a protein. (Occurs in more than 95% of human genes)

The promoter and terminator regions of genes are important in:

Promoter region signals for activating transcription of a gene or inhibiting its transcription. The terminator region of a gene marks the ending of transcription. -It does not code for amino acids. It signals for the location of activate site during transcription. *promoter and terminator region are required to control the genes* Promoters tell about the gene protein that should or should not be made, otherwise there would be no order in which proteins are produced.

Why is PCR so revolutionary? Describe two applications of PCR when you're doing DNA sequencing.

Revolutionary because the DNA doesn't have to be purified and can be present in minute amounts; even a single DNA molecule can be a starting point. you can see if two DNA strips are the same - i.e. DNA tests - forensics mutation detecting

Repressor Protein

Proteins that prevent transcription by binding to the same DNA sites that transcription activators would normally use or by interfering with the activities of the group of enzymes that kick off transcription. DNA is prevented from unwinding and the genes are kept turned off

Proto-oncogene vs. oncogene. What processes or events can cause a proto-oncogene to become an oncogene?

Proto-oncogenes: proteins that start or maintain cell growth/division--cells grow and divide when active -When porto-oncogenes are inactivated, normal cells stop dividing and produce oncogenes: mutant forms of porto-oncogenes that give constant signals for cells to keep dividing uncontrollably

Ribosomal RNA (rRNA)

RNA molecules that form part of the ribosome and *site of polypeptide synthesis*

The enzyme that copies the gene during transcription is

RNA polymerase

The enzyme that copies the gene during transcription is ___

RNA polymerase

What are some environmental factors that can cause mutations?

Radiation, chemicals, (complete)

Telomeres

Short repeated DNA sequences located at each end of chromosomes --Regulates number of cell divisions

What is meant by "reading frame", and list two types of mutations that can change the reading frame.

Reading frame: way of dividing sequence of nucleotide (in DNA or RNA) molecule into a set of consecutive, non overlapping triplets. Where these triplets equate to amino acids or stop signals during translation, they are called codons. Mutations: -Insertion: insertion changes the number of DNA bases in a gene by adding a piece of DNA. The protein made by the gene may not function properly as a result -Deletion: changes number of DNA bases by removing a piece of DNA. Small deletions may remove one or a few base pairs within a gene, while larger deletions can remove an entire gene or several neighboring genes. Deleted DNA may alter the function of the resulting proteins. -Duplication: Consists of a piece of DNA that is abnormally copied one or more times. This type of mutation may alter the function of the resulting protein

Transgenic

Refers to transfer of genes between species by recombinant DBA and technology; transgenic organisms have received such a gene

Promoter

Regulatory region located at the beginning of a gene- a region of a DNA molecule to which RNA polymerase binds and initiates transcription -binds the protein complexes that copy the DNA to form mRNA.

Deletion

Removal of a base which shifts the *reading frame*

Telomeres are shortened after each round of __

Replication

In the creation of a DNA profile, what type of DNA is used?

Short tandem repeats

RNA

Ribonucleic acid -- made of nucleotides *Principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins* -Several forms of RNA function in gene expression -found in nucleus and cytoplasm

Golden rice

Rice produced by genetic engineering that contains a precursor to vitamin A and is used in fighting vitamin A deficiency, which causes blindness and health problems in many parts of the world

Most protein synthesis happens on the surface of the ___________.

Rough endoplasmic reticulum

Polypeptides are made on the

Rough endoplasmic reticulum and have sorting signals that direct them to their proper locations within the cell.

Genetic imprinting

Selective use of either the maternal or paternal copy of a gene -caused by epigenetic changes to DNA -Not a mutation or a permanent change in the DNA or chromosome region. *affects the expression of a gene, not the gene itself* -does not affect all genes--only genes in certain regions of seven human chromosomes are imprinted

Short tandem repeats (STRs)

Short nucleotide sequences 2 to 9 base pairs long found throughout the genome that are organized into clusters of varying lengths; used in construction of DNA profiles

Primer

Shorts strand of DNA or RNA that serves as a starting point for DNA synthesis. It is required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA.

Compare and contrast DNA and RNA. Explain 3 similarities and 3 differences

Similarities: -Both are made up of monomers called nucleotides, and have Adenine, Cytosine, and Guanine in common (DNA has Thymine, and RNA has Uracil) -Cytosine pairs with Guanine in both -Both are necessary to make proteins -Both have pentose sugars Differences: DNA - Stores RNA and protein-encoding information, and translates information to daughter cells - Double stranded - Very Stable - The sugar on the nucleotide is deoxyribose - Has Thymine as its fourth base RNA -Carries protein-encoding information and helps to make proteins -Single Stranded -Not Stable -The sugar on the nucleotide is ribose -Has Uracil as its fourth base

Chromatin remodeling

Specific proteins bind to DNA to unwind it and unwrap DNA from the nucleosomes so that genes can be turned on. Push histones aside to free up DNA for transcription.

Alternative splicing

Splicing of RNA transcripts (variations in mRNA) from the same gene in different ways, each of which produces a distinct protein

How does the ribosome know where to start translation? How does it know where to stop?

Start codon, AUG is the only codon that tells the ribosome where to start translation. The stop codon (UAA, UAG, and UGA) terminate translation.

How might stem cells be used to treat disease? What types of disease would be treated with the use of embryonic stem cells? Adult stem cells? Why/how are these different?

Stem cells can be induced to form specific cell types with specialized functions. Some diseases are caused by the death of one or a small number of cell types and could be treated with pluripotent stem cells. - Ex: Parkinsons, Huntington, Type I diabetes -Adult stem cells have limited developmental potential, are rare and difficult to isolate, and are more difficult to grow and reprogram than embryonic stem cells.

Cortisol

Steroid hormone that influences gene expression by combining with its receptors. Glucocorticoid receptors are far more abundant and distributed more widely than androgen receptors -transmitted to fetus through placenta, permanently adjusting the settings of the stress axis of the fetus in a way that makes it more sensitive to hyper responsive and subsequent stressful events

Do stop and start codons code for any amino acids?

Stop: UUA, UGA, UAG--doesn't code Start: AUG--methionine

____ are on outside of the helix and ___ are stacked on the inside

Sugars and phosphates, nitrogenous bases (genetic information in these bases--*have high coding capacity*) -Amount of adenine=amount of guanine=amount of cytosine

A pairs with ____ in opposite chain, and C pairs with ___

T, G

RNA polymerase uses the __ strand of the DNA to make a copy of the gene

Template

RNA polymerase uses the ___ strange of DNA to make a copy of the gene

Template

Mis-regulation of the cell cycle is an important component of most cancers T/F

True

What is the evidence that some cancers might be caused by the environment, rather than being inherited? What are some of the environmental causes of cancer? What are the potential mechanisms by which these environmental factors contribute to cancer risk?

The Cancer genome atlas and research in epigenetics. SOME CAUSES: Certain viruses, radiation, chemicals, infections, as well as lifestyle choices and behaviors such as diet, sun exposure, and tobacco. Analysis of the patterns of DNA methylation are used to distinguish invasive from noninvasive forms of cancer and to diagnose subtypes. Resistance can develop based on these environmental factors.

Chromatin

The DNA and protein components of chromosomes, visible as clumps or threads in nuclei

Briefly describe what you know about the structure of DNA and how DNA is packaged in a cell and describe at the molecular level ONE epigenetic mechanism that can affect DNA packaging and gene expression.

The DNA structure is a double helix made up of phosphates, sugars, and bases. Long strings of packaged DNA is wrapped around histones which forms chromatin. Gene expression depends on how tightly the DNA is wound around the proteins. Methylation is an epigenetic mechanism that can affect DNA packaging and gene expression. During methylation, additional methyl groups are added to bases in DNA which turn genes off (silencing). The presence of methyl groups may prevent transcriptional proteins from binding to the gene while methylated DNA binds to non-histone proteins that promote inactive (or silenced) chromatin.

Nucleotide

The basic building block of DNA and RNA. Each nucleotide consists of a base, a phosphate, and a sugar -linked to a phosphate group

Position effect

The effect on the expression of a gene when its location in a chromosome is changed, often by translocation

DNA Polymerase

The enzyme that replicates DNA

Most of the genes encoded in the nucleus of each of our cells are much larger than the corresponding mRNAs found in the cytoplasm. Explain why this is so, and what advantage this might have to the cell.

The genes inside the nucleus have introns in them, these do not code for amino acids, and they have exons. In mRNA it can take from the same gene strand but use different exons to make different forms of a proteins Nucleus: A poly-A tail is added to many maturing mRNAs. When poly-A tails are made longer, there is increased translation, producing more protein molecules per mRNA Cytoplasm: Enzymes can lengthen or shorten the poly-A tail When poly-A tails are shortened, translation of proteins from those mRNAs is decreased

How can a human cell (which contains only about 21,000 genes) create over 1 million different kinds of proteins? (hint: see figures 9.5 and 9.14)

The large pre-MRNA precursor molecules are processed in the nucleus to remove introns, nucleotide sequences present in genes that are not translated into amino acids, introns are between exons, which are DNA sequences that are transcribed joining other exons and translated into the amino acid sequence of a protein, As introns are removed, the exons are spliced together to form mature mRNA molecules. In alternative splicing, exons can be retained or removed during splicing, allowing mature mRNA to contain different combinations of exons. This allows one gene to encode information for several different forms of protein.

What biochemical property do histone proteins have that help them to bind DNA? What is their role in chromatin formation?

The major class of proteins in chromatin is histones which plays important roles in chromosomal structure and gene regulation. At the lowest end of chromosome organization, DNA is wound around a core of histone molecules to form small spherical bodies called nucleosomes. -Winding DNA around histones compacts the DNA through folding and compaction -Chromatin folds into loops and fibers that attach to and extend from a central protein -histone protein is positive charged and DNA is negatively charged--They have a positive charge to help them bind to the negative charge of the phosphate groups 8 histones will attach to the DNA to form a nucleosome which will then stack on top of one another to form chromatin

How can a mutation in a region o fDNA that does not code for protein result in too much, too little, or the wrong sized protein being made? (think about regulatory sequences and important non-coding regions of genes)

The mutation can occur in a start codon (leading to the sequence never being read) or in a stop codon (making a sequence that is too long)

Which of the following best describes the effect of cancer-causing mutations on the cell cycle?

The mutations cause the cell to bypass checkpoints in the cycle.

DNA polymerase

The name of the enzyme that replicates DNA--adds nucleotides at the 3' carbon. (Synthesis proceeds only in the 5' to 3' direction)

Mutation rate

The number of events the produce mutated alleles per locus per generation -can be measured: -only by *dominant alleles* and only under certain conditions: must never be produced by recessive alleles, always be fully expressed so the mutant individuals can be identified, have clearly established paternity, never be produced by non genetic agents such as drugs/infections, be produced by a dominantly inherited mutation of only one gene -almost impossible to measure directly the mutation rates in autosomal recessive alleles by pedigree analysis, but DNA sequencing and other genomic techniques are useful

Template

The one that is READ-- 3'---5' 5' to 3' is coding

pre-messenger RNA (pre-mRNA)

The transcript made from the DNA template that is processed and modified to form messenger RNA

Chromatin remodeling

The set of chemical changes to the DNA and histones that activate and inactivate gene expression -activated genes can be inactivated by reversing histone modification and removing the chemical groups added during activation. This process is reversible (chromatin remodeling) and is one of the main mechanisms of gene regulation in humans and other eukaryotes *reversible process

Most cancers are caused by sporadic mutations (T/F)

True

Epigenetics

The study of reversible chemical modifications of chromosomal DNA (such as methylation of bases) and/or associated histone proteins that change the pattern of gene expression without affecting the nucleotide sequence

How are transgenic animals used? What is their advantage in medicine?

The transfer of genes between species. An organism that has received a gene from another species by means of recombinant DNA technology. -Transgenic mice are a common model system for human diseases -Transfer of disease-causing human genes into mice creates mice that are used to study: -The development of human diseases. -The effects of drugs and other therapies

Biotechnology

The use of recombinant DNA technology to produce commercial goods and services

RNA polymerase adds nucleotides to the 3' end of the RNA molecule (T/F)

True

Chemical analysis shows that a nucleic acid sample contains A, U, C and G. Is this DNA or RNA and why?

This is RNA because only RNA has Uracil, instead of Thymine.

Enhancer DNA

This type of gene sequence turns on transcription and speeds it up, making transcription happen faster and more often. Can be upstream, downstream, or even in the middle of the transcription unit. Have the unique ability to control genes that are distantly located. Only influence genes that are normally activated in that particular cell type

Specific aneuploidies are associated with various cancers (T/F)

True

DNA--> mRNA

Transcription

Transcription

Transfer of genetic information from the base sequence of DNA to the base sequence of RNA, mediated by RNA synthesis

GMOs

Transgenic plants or animals created by recombinant DNA techniques

Ribosome

Translates genetic information in the RNA into a string of amino acids that will become a protein--can make any kind of protein *Cytoplasmic particles that aid int he production of protein *Site of polypeptide synthesis

mRNA--> Protein

Translation

Codon

Triplets of nucleotides in mRNA that encode the information for a specific amino acid in a protein

A single cancers tumor can have multiple genetic changes within the cells that make up the tumor T/F

True

Acetylation and methylation are mechanisms of chromatin remodeling (T/F)

True

Cell signaling molecules only have an effect in cells with receptors for the signaling molecule (T/F)

True

Changes in chromosome number and structure such as aneuploidy are typical of cancer cells (T/F)

True

Alternative splicing is the mechanism for making more proteins than there are coding genes (T/F)

True--removes all intron sequences and then joins up the eons to create an mRNA that does for a continuous run of amino acids *splicing enables a cell to use a relatively small number of genes to create a much bigger number of proteins

Acetylation increases gene transcription (T/F)

True--turns on

in RNA, there is no T so an A in the DNA template ends up as a ___

U. CGGATCAT turns into GCCUAGUA

Hemophilia

Uncontrollable episodes of bleeding

Polymerase Chain Reaction

Uses repeated cycles of heating and cooling to make many copies of a specific region of DNA *sections of a DNA molecule, rather than the whole molecule, are copied

How is DNA used for identification? How are STRs used to create a DNA profile?

Uses variations in the length of short repetitive DNA sequences. Identify individuals with a high degree of accuracy and reliability. Short tandem repeat/STRs range from 2 to 9 base pairs in length (CCTTCCCTTCCCTTCCCTTCCCTTCCCTTC) contains six repeats of the CCTTC sequence. Repeat numbers vary between individuals. A unique profile can be produced by analyzing several STRs in a DNA sample. In each individual the number of repeats differs. In the US, a standard set of 13 STRs (CODIS) is used to prepare a profile

Hydrogen bond

Weak (and can be easily broken) interactions between two atoms (one of which is always hydrogen) that carry partial but opposite electrical charges. *Hold together the two strands of a DNA molecule

Silent mutation

When the mutation does not change the phenotype *Same amino acid*

Gain of function mutation

a *mutation* that confers new or enhanced activity on a protein

Degenerate codon

a codon that specifies the same amino acid as another codon.

Polymerase chain reaction

a method for amplifying DNA segments using cycles of denaturation, annealing to primers, and DNA polymerase-directed DNA synthesis

Hormone receptor protein

a molecule that can bind to a specific hormone.Receptors for peptide hormones tend to be found on the plasma membrane of cells, whereas receptors for lipid-soluble hormones are usually found within the cytoplasm

conditional mutation

a mutation that has the wild-type phenotype under certain (permissive) environmental conditions and a mutant phenotype under other (restrictive) conditions

Duplication

a piece of DNA that is abnormally copied one or more times. This type of mutation may alter the function of the resulting protein

What is a negative feedback loop and how might it help prevent chronic stress?

a regulatory mechanism in which a 'stimulus' causes an opposite 'output' in order to maintain an ideal level of whatever is being regulated. Cortisol is a "stress" hormone. In healthy individuals, cortisol turns off the gene that signals for the production of more cortisol - "negative feedback loop" attempt to stabilize and regulate Glucocorticoid Receptor Protein (GRP) helps shut down the stress response

What is a "negative feedback loop" and how might it help prevent chronic stress?

a regulatory mechanism in which a 'stimulus' causes an opposite 'output' in order to maintain an ideal level of whatever is being regulated.Cortisol is a "stress" hormone. In healthy individuals, cortisol turns off the gene that signals for the production of more cortisol - "negative feedback loop" attempt to stabilize and regulate Glucocorticoid Receptor Protein (GRP) helps shut down the stress response

DNA microarray

a series of short nucleotide sequences put on glass that can be used to detect mutant genes or differences in patterns of gene expression

miRNA

a small non-coding RNA molecule (containing about 22 nucleotides) found in plants, animals, and some viruses, which functions in RNA silencing and post-transcriptional regulation of gene expression

Transgenic animals are valuable in the study of human diseases for which of the following reasons?

a. They can be cloned and thus have identical genomes. b. They can be used to test drugs on. c. All of these are reasons why transgenic animals are valuable in the study of human diseases. d. They can manifest the same symptoms as human diseases. e. They can be used to study the development and progress of human diseases.

Methylation

addition of a methyl group to a DNA base or a protein -reversible and do not change the base sequence of the modified DNA (so it is not a mutation) -

Philadelphia chromosome

an abnormal small chromosome sometimes found in the leukocytes of Leukemia patients. Caused by the translocation of chromosomes 9 and 22

When cancer cells develop:

as cells become more and more abnormal, old or damaged cells survive when they should die, and new cells form when they are not needed

DNA repair

collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome.

Hormones

complex chemicals that control gene expression.

Explain what is meant by the statement "Every gene has a control panel and a coding sequence"

control panels contain instructions to tell the cell how to switch genes on and off (start or stop codons). Coding sequences have information for specific amino acids. Three groups of nucleotides is called a codon, which code for the amino acid. There are 3 that do not code called stop codons, end of protein synthesis. 1 start codon AUG encodes information for amino acid (methionine) and always first codon. (pg. 197)

What cells are responsible in cancer?

epithelial cells: breast, skin, colon, lung, etc. *why do these type of cells cause most cancers? any duct in which things are moving through is going to be exposed to other things and these cells are dividing a lot

BRCA1/BRCA2

human genes that produce tumor suppressor proteins. These proteins help repair damaged DNA and, therefore, play a role in ensuring the stability of the cell's genetic material. two major breast cancer susceptibility genes-cause double stranded breaks in DNA and prevents the fixing of DNA which will lead to uncontrolled cell growth

In what way does DNA polymerase build DNA

in a 5' to 3' direction

Difference between codons and anticodons

mRNA contains codons, which specifies which amino acids to be used in making a protein. tRNA are RNA that contains the anticodon which attaches to the codon of mRNA to make proteins. They are complements of codons

What are the three major classes of RNAs in the cell, what does each type of RNA do?

mRNA: Single-stranded complementary copy of the amino-acid coding nucleotide sequence of a gene *carries genetic information into the cytoplasm- which will be encoded into the sequence of amino acids (messenger) tRNA: a small RNA molecule that contains a binding site for a specific type of amino acid and has a three-base segment known as an anticodon that recognizes a specific base sequence in messenger RNA * brings amino acids to the mRNA ribosome complex during translation. Each tRNA molecule has two attachment sites: 1st a nucleotide sequence of 3 nucleotides called anticodon which pairs with a complementary codon sequence in mRNA and 2nd a site for attachment of the amino acid specified by the mRNA codon (transfer) rRNA: RNA molecules that form part of the ribosome *the site of polypeptide synthesis- during translation the rRNA in the large subunits acts as an enzyme linking amino acids together to form a polypeptide (ribosome)

Proteins are:

made in the cytoplasm but are present in all parts of the cell: nucleus, cytoplasm, internal membranes, and the plasma membrane

Replication takes place before ___

meiosis and mitosis

Each polypeptide chain begins with ___

methionine--the amino acid made of the start codon AUG

Make the complementary strand for the following DNA template and label both strands as 5' to 3' or 3' to 5'. Draw an arrow showing the direction of synthesis of the new strand. How many hydrogen bonds are in this double strand of DNA? template: P--AGGCTCG--OH

new strand: 3' OH--TCCGAGC--P 5' The chemistry of the nitrogenous bases is really the key to the function of DNA. It allows something called complementary base pairing. You see, cytosine can form three hydrogen bonds with guanine, and adenine can form two hydrogen bonds with thymine. AT = 2 H bonds CG = 3 H bonds 7 hydrogen bonds, 1 bond between bases on each strand (like the steps on a ladder).

The "control panel" of a gene includes the

promoter and transcription factor binding site

Transcription factor

proteins involved in the process of converting, or transcribing, DNA into RNA.

Hypothalamic pituitary gonadal (HPG Axis)

refers to the effects of the hypothalamus, pituitary gland, and gonads as if these individual endocrine glands were a single entity as a whole. critical part in the development and regulation of a number of the body's systems, such as the reproductive and immune systems. Fluctuations in the hormones cause changes in the hormones produced by each gland and have various widespread and local effects on the body. This axis controls development, reproduction, and aging in animals

Loss of function mutation

result in reduced or abolished protein *function*

Epigenetic modifications

specific to a cell type, and during embryonic development, these changes help define which genes will turn on and which will not -can add or remove chemical groups to DNA bases in and near promoter region (such as methylation) -activate or silence genes

Malignant tumors

spread into nearby areas (while benign tumors do not)

Termination occurs when the ribosome reaches a ___

stop codon

Anabolic steroid

synthetic forms of androgens, particularly testosterone, and are designed to mimic testosterone for the purpose of muscle growth -the body adjusts to unnaturally high levels of testosterone by shutting down its own production of testosterone -each cell type in the body has its own control mechanisms that determine which genes, out of the entire suite of genes that possess a steroid response element, are able to respond to the presence of the steroid.

mRNA is read by ___ three bases at a time

tRNA

mRNAs bind with ___ and ___ acts as an enzyme that forms a peptide bond between the two amino acids

tRNAs, rRNAs

RNA polymerase

the enzyme that catalyzes transcription (it binds with a promoter during the initiation stage of transcription)

What are the three modifications made to pre-mRNA molecules before they become mature mRNAs, are transported from the nucleus to the cytoplasm, and become ready to be used in protein synthesis? what is the function of each modification?

the pre-mRNA of a transcription has both exons and introns. As the pre-mRNA is leaving the nucleus, following modifications are made: -Poly A tail (consisting of multiple A's) is added to the 3' end -5' Cap is added to the 5' end -Both structure help RNA to exit nucleus and prevent from being degraded -Introns are removed and exons remain intact. Exons are the only region, which is translated by ribosomes into polypeptides

Template strand

the single stranded DNA that serves to specify the nucleotide sequence of a synthesized polynucleotide strand--DNA strand with 3'-5' polarity, acts as template for transcription, codes for mRNA

Coding strand

the strand of DNA that is *not used for transcription* and is identical in sequence to mRNA, except it contains uracil instead of thymine-- 5'-3' polarity

RNA differs from DNA in

the type of sugar found in the nucleotide, the types of pyrimidine bases, and its single-stranded nature.

Activator protein

transcription factor that increases gene transcription of a gene or set of genes.

One of the concerns with the use of genetically-engineered, herbicide resistant crops is:

transfer of herbicide resistance to weeds

Translocation

transfer of part of a chromosome to a different position especially on a nonhomologous chromosome; especially : the exchange of parts between nonhomologous chromosomes

Proto-oncogene vs. Tumor supressor gene

tumor suppressor genes normally act like "brakes" to inhibit cell growth and division, and proto-oncogenes normally act like "gas pedals" to accelerate cell growth and division.

Chromosome rearrangement

type of chromosome abnormality involving a change in the structure of the native chromosome. Such changes may involve several different classes of events, like deletions, duplications, inversions, and translocations.

DNA fingerprint

use mini satellites to identify individuals

Angiogenesis

when blood vessels attach to a tumor and *provide* it with oxygen→ if this oxygen is taken away, the tumor can't survive