Modern Biology Exam 3

Define inheritance, gene, allele, homozygous, heterozygous, dominant, recessive, polygenic, pleotropic,

- Inheritance - is the process by which the traits of organisms are passed to their offspring. - Gene = a unit of heredity that encodes information needed to produce proteins - Alternative versions of genes found at the same gene locus are called alleles - The location of a gene on a chromosome is called its locus or loci - Homologous or Homozygous chromosomes carry the same kinds of genes for the same characteristics. - Each chromosome that carries a different allele of a gene is a heterozygous organism. - When two different alleles are present in an organism, the dominant allele may mask the recessive allele, even though the recessive allele is still present. - Polygenic Inheritance - a pattern of inheritance in which the interactions of two or more functionally similar genes determine phenotype. - Some alleles of a characteristic may have multiple phenotypic effects (pleiotropy) influencing a number of gene loci

Many crosses begin by crossing two "pure breeding" parents, what does "pure breeding" mean? -Pure breeding is the same thing as True breeding

- Pure breeding is the same thing as True breeding - True-breeding organisms possess traits that remain inherited unchanged by all offspring produced by self-fertilization

What is gene linkage?

-Alleles that are on the same chromosome do not line up independently of one another on the metaphase plate and are not separated at anaphase I. Therefore, genes on the same chromosome tend to be inherited together. -What are the expected gametes from parent PpLl, where P is linked with L and p is linked with l? The gametes are mostly PL and pl (not 1/4 PL, 1/4 Pl, 1/4 pL, 1/4 pl)

What are the three methods utilized in identifying the presence and spread of cancer?

-Biopsy needle -CT scan -MRI

What are the three most commonly diagnosed cancers in the United States, regardless of sex?

-Breast (29%) -Prostate (26%) -Lung and bronchus (14%M, 13%F)

How does a cancer make you sick?

-Cells are carefully regulated and organized; cell proliferation (production) is balanced with cell death. Cancer destroys that balance and causes cells to grow and reproduce excessively instead of dying. -Metastasis is when cancer cells enter the bloodstream producing secondary tumors hat spread through the body. -Angiogenesis happens when blood cells are routed to the tumor, depriving normal cells from the oxygen they need.

How does crossing over create new patterns of gene linkage?

-Crossing over involves the exchange of DNA between chromatids of paired homologous chromosomes in synapses (the tight association of homologous chromosomes on the metaphase plate). It creates new combinations of linked alleles. -the further they are, the more likelihood the crossing over would happen between them making them completely different from what we would expect -HIGH genetic variability -Prophase 1 of meiosis: crossing over or genetic recombination creates new gene combinations

How is cancer both a hereditary disease as well as a disease that is influenced by the environment?

-Genetic mutations in the DNA can be transmitted from parents to their kids; these mutations can include the type that causes carcinogenic cells. -Example: Xeroderma pigmentosum is a genetically inherited disease in which cells have deficient ability to repair damage caused by UV light, leading to high risks of skin cancer -Environmental factors such as food, drugs, or exposure to toxins can cause epigenetic changes by altering the way molecules bind to DNA or changing the structure of proteins that DNA wraps around. These structural changes can result in slight changes in gene activity; they also can produce more dramatic changes by switching genes on when they should be off or vice versa. -Examples: benzene, a known cause of human leukemia, is a common pollutant in vehicle exhaust. Arsenic, linked to skin, liver, bladder and lung cancer, contaminates some drinking water supplies. Other known human carcinogens include asbestos, hexavalent chromium, aflatoxins and vinyl chloride.

Know, in detail, how ABO blood typing works and how this applies to codominance.

-Human blood types are an example of multiple alleles of a single gene. Human blood group genes produce blood types A, B, AB, and O. -A and B code for enzymes that add different sugar molecules to the ends of glycoproteins that protrude from red cells. O codes for a nonfunctional enzyme that doesn't add any sugar molecules. -Type A: AA or AO genotypes (can accept A or O donations) -Type B: BB or BO genotypes (can accept B or O donations) -Type O: OO genotypes (Universal Donor, but can only accept O donations) -Type AB: AB allele (universal recipient) -Codominance: when heterozygotes express the phenotypes of both of the homozygotes (like the A B glycoproteins).

Define apoptosis? Know that this cancer cells do not undergo this process.

-In a normal cell, Apoptosis is the programmed cell death. -In cancer cells the signals that trigger apoptosis are ignored, which prevents it from getting killed.

Understand that in cancer, the dividing cells skip all normal cell cycle check points and continue dividing uncontrollably.

-In a normal cell, Apoptosis is the programmed cell death. -In cancer cells the signals that trigger apoptosis are ignored, which prevents it from getting killed. Understand that in cancer, the dividing cells skip all normal cell cycle check points and continue dividing uncontrollably. -Checkpoints regulate progress through the life cycle, ensuing that he cell successfully completes DNA synthesis during interphase, and proper chromosome movements occur during mitotic cell division. -G1 checkpoint: checks if raw materials are available for cell division and determines whether or not the cell continues through the entire cell cycle (some cells never divide, like neurons or red blood cells). -G2 ensures there was proper DNA replication- if it wasn't copied properly it tries to repair it or the cell has to die (apoptosis) instead of continuing. -M checkpoint makes sure that the spindles attached properly (divided evenly at the centromere). If not even, daughter cells end up without the right amount of chromosomes.

Explain incomplete dominance? How does this relate to the phenotypic and genotypic make-up of the individual?

-Incomplete dominance= the phenotype of the heterozygotes (Aa Bb) is intermediate between the phenotypes of the homozygotes (AA BB).

What are the three basic differences between cancer cells and normal cells?

-Normal cells communicate via chemical signals that influence cell division and program cell death. Cancer cells lack effective communication. -Normal cells stop dividing at a certain density (fill the spot and sop). Cancer cells keep dividing regardless of density. -Normal cells only divide a certain number of times and then die. Cancer cells are not programed to die.

How can the environment regulate phenotype?

-Siamese cats have the genotype for dark fur all over its body, however, the enzyme that produces the dark pigment is only activated when exposed to temperatures below 93`F (34`C). Siamese cats are born white and the ears, nose, paws and tail become dark when they become cooler than the rest of the body.

When cancer is diagnosed, it is staged based on tumor size, lymph node affected, and metastases. The lower the number, the better the prognosis. What are the general conditions for each stage?

-Stage I: Localized Cancer- Cancer is limited to the organ in which it began, without evidence of spread -Stage II and III: Regional Spread- Cancer has spread beyond the primary site to nearby lymph nodes or tissues and organs -Stage IV: Distant spread- Cancer has spread from the primary site to distant tissues or organs or to distant lymph nodes

What are the three standard forms of treatment and what are the goals of each treatment?

-Surgery -The only curative therapy for many common solid tumors. The most important determinant of a successful surgical therapy is the absence of distant metises and no local infiltration. -Radiation -success depends on the sensitivity difference between the tumor and normal tissue. It involves administration of ionizing radiation in the form of x-ray or gamma rays to the tumor site. -there are short and long term toxicity complications that result from radiation. It is known to be mutagenic, carcinogenic, teratogen (cause birth defects), and having increased risk of developing both secondary leukemia and solid tumor. -Chemotherapy -Halts cell division. Every chemotherapeutic will have some deleterious side effects on normal tissues.

Explain the relationship between the P, F1, and F2 generations.

-The true breeding parents are the P Generation. -The hybrid offspring of the P generation are called the F1 generation. -When F1 individuals self-pollinate, the F2 generation is produced.

What is the difference between a tumor and a cancer?

-Tumor is a benign abnormal cell growth of tissue that is capable of forming a mass. -Cancer is a malignant cell growth with the potential to invade or spread to other parts of the body.

Be able to explain the process of binary fission.

1. Parent cell contains one chromosome 2. DNA replicates and attaches to cell membrane 3. Membrane growth between the 2 attatchment points moves the DNA molecules apart as new cell wall material is deposited 4. The result of this is two daughter cells, each identical to the original.

What is apoptosis and how is it different from cell division?

Apoptosis, or programmed cell death, is a naturally occurring process in the body. It involves a controlled sequence of steps in which cells signal self termination. Apoptosis works to keep the body's natural cell division process of mitosis in check. -cell death, carves out distinctive structures-getting rid of damaged cells by killing them.

Cell division is the process of dividing a parent cell into two identical daughter cells. How is the process different in sexual versus asexual reproduction?

Asexual reproduction is reproduction without sex. In this form of reproduction, a single organism or cell makes a copy of itself. The genes of the original and its copy will be the same, except for rare mutations. They are clones. The main process of asexual reproduction is mitosis. This type of reproduction is common among some single-cell organisms, for example, amoeba. Many plants also reproduce asexually Sexual reproduction is a way of reproduction of some animals and plants. Some protists and fungi also reproduce this way. Organisms that reproduce sexually have two different sexes: male and female. Offspring is made by a cell from the male and a cell of the female. Different steps are involved in the process. The cells of an animal or higher plant have two sets of chromosomes: they are diploid. When gametes (sex cells) are produced, they have only one set of chromosomes: they are haploid. They have undergone a process of cell division called meiosis. During meiosis, crossing over occurs. This makes it possible to get recombination. This has various consequences. It means, for example, that all the children of two parents are not identical, except in the rare case where they developed from the same fertilized egg. The second step is called fertilization. In it, the two cells merge into one. This restores the diploid state.

Cancer is caused by what underlying reason(s), regardless of cancer type?

Cancer is a disease of uncontrolled cell growth. It happens when cells either grow too much too fast, or they cannot stop reproducing. These genetic mutations can be inherited r attributed to the environment.

What is the difference between chromosome, chromatid, and chromatin? When in the cell cycle will you find each one?

Chromosome: a continous molecule of DNA wrapped around protein in the nucleus of a eukaryotic cell, also the genetic make up for a prokaryotic cell -found all throughout Chromatid: one of 2 identical DNA molecules that make up a replicated chromosome - found in Anaphase, Chromatin: collective term for all of the DNA and its associated proteins in the nucleus of a eukaryotic cell

Describe semi-conservative replication.

DNA replication begins simultaneously at multiple origins of replication

Understand the process of how genes are placed in each gamete. If a parent is Pp, then the gametes can be either P or p.

Gamete = a reproductive cell, as a sperm or egg, that unites with another cell to form a new organism. Ex: If parent is PP then the gamete can either be P or P. If a parent is Pp, then the gamete can either be P or p.

Define homologous chromosome, sister chromatid, haploid, diploid, autosome, sex chromosomes.

Homologous Chromosome: Sister Chromatid: Haploid: Diploid: Autosome: Sex Chromosome:

What are the stages and general activities of each step of the cell cycle? How does mitosis differ from the cell cycle?

Interphase (g1, g0, g2, s) Mitosis ( prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis) Centrosome spindle kinetochore

What is the first step in all cell division processes?

Interphase- stage where the chromosome replicate and the cell grows

How does sexual reproduction improve likelihood of surviving ecological disasters?

It increases the chance that some offspring survive in changing environments.

Independent Assortment

It states that the alleles of one gene sort into the gametes independently of the alleles of another gene.

How are leading and lagging strands formed?

Leading: on one strand, DNA polymerase follows helicase as it unzips the DNA. Continues in a 5' to 3' direction. its continous Lagging: DNA polymerase adds nucleotides in the opposite direction of the helicase movement. it is discontinous.

How many rounds of DNA replication occur in meiosis?

One

Be able to describe, in detail, what is occurring in the four steps of mitosis (prophase, metaphase, anaphase, and telophase/cytokinesis). For our purposes, include cytokinesis as part of telophase.

Prophase: stage when chromosomes condense and become visible and the spindle begins to form Metaphase: chromosome are aligned down the center Anaphase: the spindle pulls the sister chromatids toward opposite poles Telophase: chromosomes arrive at opposite poles and nuclear envelopes form. distribution of cytoplasm to daughter cells following the division of the cell's chromosomes. cleavage furrow: indentation in cell membrane of an animal cell undergoing cytokinesis cell plate: material that forms the beginnings of the cell wall in a plant cell undergoing cytokinesis

Understand the general mechanism of DNA replication. What are the three components needed? What are the names of the enzymes involved and what are their functions?

Step 1: stand unwinds and separates Step 2: Each strand is a template that attracts and binds complementary nucleotides. (A with T and G with C) Step 3: Each double stranded DNA molecule consists of 1 parental and 1 daughter strand, as a result of semiconservative replication DNA Enzymes: Helicase unwinds double helix Binding Proteins stabilize each strand Primase adds short RNA primer to template strand DNA polymerase binds nucleotides to form new strands Ligase creates covalent bond between adjacent DNA segments

How many rounds of cell division occur in meiosis?

Two

Define a clone?

an organism or cell, or group of organisms or cells, produced asexually from one ancestor or stock, to which they are genetically identical.

If given the number of chromosomes in any give stage of the cell cycle, can you tell me the diploid number? If there are 40 chromosomes in G2, what is the diploid number?

diploid number is always double the haploid number. -80

How does cytokinesis differ in plant and animal cells?

in animal cells, microfilaments attached to the plasma membrane form a ring around the equator of the cell. in plant cells, a new plate wall is formed and then complete the separation of the daughter cells.

When does mitosis occur and what is the outcome of mitosis (how many chromosomes, etc)?

mitosis occurs after interphase. double the chromosomes

Understand the eukaryotic cell division is inherently more complex simple because there is more DNA, the DNA is longer, and the way DNA is packaged is more complex.

ok

What is an Okazaki fragment?

short sections of DNA

When DNA is packaged as a chromatid, what is the function of the centromere and telomeres?

telomeres: essential for chromosome stability centromeres: temporarily holds 2 daughter DNA double helices, the attachment site for microtubules that move the chromosomes

What is a karyotype?

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species

What is an origin of replication?

where the replication begins