Bio 111 Exam 3 Chapter 10, 11, 12

Parental/F1/F2 generations

P means parental generation. F1 means first generation (children of P), and F2 means second generation, which are the grandchildren of P.

How to set up and understand Punnett Squares.

Parent one gene on top Parent two gene on side Offspring in middle boxes

Know how polygenic inheritance works.

Polygenic inheritance occurs when one characteristic is controlled by two or more genes. Often the genes are large in quantity but small in effect. Examples of human polygenic inheritance are height, skin color, eye color and weight.

Each Phase of Meiosis and the major events that occur during each phase.

Prophase I: The chromosomes condense, and the nuclear envelope breaks down. crossing-over occurs. Metaphase I: Pairs of homologous chromosomes move to the equator of the cell. Anaphase I: Homologous chrmosomes move to the oppisite poles of the cell. Telophase I: and Cytokinesis Chromosomes gather at the poles of the cells. the cytoplasm divides. Prophase II: A new spidle forms around the chromosomes. Metaphase II: Chromosomes line up at the equator. Anaphase II: Centromeres divides. chromatids move to the opposite poles of the cells. Telophase II and Cytokinesis: A nuclear envelope forms around each set of chromosomes. the cytoplasm divides.

Each Phase of Mitosis.

Prophase, Metaphase, Anaphase, Telophase, Cytokinesis, Interphase

The major events that occur during each phase.

Prophase- The first and longest stage of mitosis. In this stage the chromosomes become visible and the centrioles separate and move to opposite poles of the cell. Metaphase- The second stage of mitosis. In this stage the chromosomes line up across the center of the cell and become connected to the spindle fiber at their centromere. Anaphase- The third stage of mitosis. In this stage the sister chromatids separate into individual chromosomes and are pulled apart. Telophase- The fourth and last stage of mitosis. During this stage the chromosomes gather at opposite ends of the cell and lose their distinct rod-like shapes. Two new nuclear membranes then form around each of the two regions of DNA and the spindle fibers disappear. Cytokinesis- The process that follows the last stage of mitosis. With two complete copies of the DNA now in two different regions of one cell, the cell membrane will pinch and divide the cytoplasm in half. The result is two individual cells that are identical to the original cell. Each of the two new cells have a complete copy of the DNA and contain all of the organelles that the original cell had. Interphase- A period of cell growth and normal activity. This period comes between mitosis in the cell cycle. Cells that do not need to replicate will spend their time in this stage. If a cell does need to divide, it will copy all of it's DNA while period. This way, the cell has two complete copies of its DNA before it begins the process of mitosis.

Given a particular cross, be able to predict the probability of an offspring occurring.

Punnet square and count

Describe the 3 ways we get genetic variation.

Random fertilization, random assortment, crossing over Random fertilization is when any possible egg can be fertilized by any possible sperm; so 8 million x 8 million means each person is one out of 64 million possible combinations, making it very genetically diverse. Crossing over is the exchange of genetic material between non-sister chromatids during synapsis of Prophase I of meiosis. This contributes to genetic diversity by combining DNA from two parents into a single chromosome. Random assortment of homologs on the cell plate is in meiosis I when the orientation of paternal and maternal homologues at the metaphase plate is random. Therefore, although each cell produced by meiosis contains only one of each homologue, the number of possible combinations of maternal and paternal homologues is 2n, where n = the haploid number of chromosomes. Random assortment of homologues in humans produces 223 (8,388,608) different combinations of chromosomes, making it very genetically diverse.

Describe the human sexual life cycle.

(Meiosis, fertilization, mitosis) Somatic cells - all the cells of the body except the germ or stem cells which are those that produce gametes (sperm and eggs). Somatic cells all contain paired chromosomes. (Diploid or 2n) Germ or stem cells are diploid and will undergo meiosis to produce four haploid (1n) gametes. Humans have 23 pairs, or 46, chromosomes that vary by size, shape, and appearance. 22 pairs are called autosomes. The other pair are the sex chromosomes. These are the X and Y chromosomes. Other species have other arrangements for sex determination. Arranging these chromosomes, by pairs, according to size and shape, results in a display called a karyotype. (Fig 13.3). Different species show different karyotypes, varying in shape, size and number of chromosomes. In humans, the gametes will have 22 autosomes and one sex chromosome. At fertilization (syngamy), two gametes will combine to cause the resultant zygote (fertilized egg) to have 44 autosomes (22 pairs) and 2 sex chromosomes (1 pair). The zygote is diploid, as were the parents.

gene

(in informal use) a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring. "proteins coded directly by genes" (in technical use) a distinct sequence of nucleotides forming part of a chromosome, the order of which determines the order of monomers in a polypeptide or nucleic acid molecule which a cell (or virus) may synthesize.

diploid

(of a cell or nucleus) containing two complete sets of chromosomes, one from each parent.

haploid

(of a cell or nucleus) having a single set of unpaired chromosomes.

Why are peas useful for genetics research?

1.garden peas have small generation period so a number of generations may b studied in a small time. 2.the characters noticed in garden pea r quite distinct and easy to recognise.like seed shape,height(tall or short),colour of pod(yellow or green),wrinkled or smooth. 3.most of the characters studied in garden pea r located on different chromrsomes so there r less chances of crossing over and more accurate results r obtained.for example the 7 traits mendel studied were located on 4 chromosomes.... 4.in garden pea the female flower may b easy covered by a plastic bag to avoid contamination by an unwanted pollen...

Determine genotypes from a given pedigree.

1st generation 2nd generation 3rd generation

benign tumor

A benign tumor is a mass of cells (tumor) that lacks the ability to invade neighboring tissue or metastasize. These characteristics are required for a tumor to be defined as cancerous and therefore benign tumors are non-cancerous

Explain: complete dominance (there may be a genetics problem on these)

A kind of dominance wherein the dominant allele completely masks the effect of the recessive allele in heterozygous condition. Bb (looks dominant)

True-breeding

A true breeding organism, sometimes also called a purebred, is an organism that always passes down certain phenotypic traits (i.e. physically expressed traits) to its offspring. If an organism has a certain characteristic that is always passed on to its offspring, we say that this organism bred true with respect to that characteristic ex: a pink flower that self pollinates will always produce pink flowers

The cycle of CDKs and cyclins.

At the G2 checkpoint, cyclin-dependent kinases (cdks) phosphorylate histones and proteins that carry the cycle past the checkpoint into mitosis. During G2, the cell gradully accumulates G2 cyclin (also called mitotic cyclin). The cyclin binds to CDK to form a complex called MPF (mitosis promoting factor). When the level of MPF exceeds the threshold necessary to trigger mitosis, the G2 phase ends and mitosis begins. One of many functions of MPF is to activate proteins that destroy cyclin. As mitosis proceeds to the end of metaphase, cdk levels stay relatively constant, but G2 cyclin is degraded, causing progessively less MPF to be available and initiating the events that end mitosis. After mitosis, the gradual accumulation of new cyclin starts the next turn of the cell cycle. The G1 checkpoint is thought to be regulated in a similar fashion. The level of G1 cyclin increases and associates with cdk. Eventually, a threshold ratio that triggers the next round of DNA replication is reached. The cyclin is degraded and the cycle begins again.

Recessively inherited disorders and examples of each

Autosomal recessive inheritance means that the gene is located on one of the autosomes (chromosome pairs 1 through 22). This means that males and females are equally affected. "Recessive" means that two copies of the gene are necessary to have the trait, one inherited from the mother, and one from the father. A person who has only one recessive gene is said to be a "carrier" for the trait or disease, but they do not have any health problems from "carrying" one copy of the gene. Ex: Cystic fibrosis sickle cell anemia, tay sachs disease

Molecules involved in cell cycle progression.

CDK and cyclin

How cancer cells behave (density-dependence and anchorage-dependence).

Cancer cells do not exhibit anchorage dependence or denisty-dependent inhibition.

How normal cells behave (density-dependence and anchorage-dependence).

Cells anchor to dish surface and divide (anchorage dependence). When cells have formed a complete single layer, they stop dividing (density-dependent inhibition). If some cells are scraped away, the remaining cells divide to fill the gap and then stop (density-dependent inhibition).

Similarities between Mitosis and Meiosis.

Chromosomes condense before they attach to the spindle. Both preceded by one round of DNA replication. Both types of cell division that occur in humans and other animals. They share many aspects, including the production of new cells and replication of genetic material. Mitosis and meiosis are the two ways by which cells reproduce. As a result, they share several steps in their respective processes. Meiosis adds another division and a step that mixes the genetic material, but in both cases the cell must duplicate its DNA, pull it apart into two sets, place the sets on each end of itself, and then divide down the middle. Both mitosis and meiosis produce fresh new cells based on their parent cells' genes.

Describe how crossing-over occurs.

Crossing over occurs during prophase I of meiosis I. It involves the switching of genes between the non-sister chromatids of homologues which allows the novel mixture of maternal and paternal genetic material with new, recombinant chromosomes.

Dominantly inherited disorders and examples of each

Dominant genetic diseases only require a single copy of the gene to be damaged. This error need only be inherited from one parent in order to get the disease. Ex: Autosomal dominant polycystic kidney disease Marfan syndrome MODY diabetes Otosclerosis

Know how epistasis works.

Epistasis is a phenomenon that consists of the effect of one gene being dependent on the presence of one or more 'modifier genes' (genetic background). Similarly, epistatic mutations have different effects in combination than individually. ex: coat color

the parts of the spindle

Fibers made of microtubules and associated proteins.

Each Phase of Cell Cycle.

G1, S, G2, and mitosis

The major events that occur during each phase.

G1- when the cell grows to its proper size. S- when the cell duplicates its DNA G2-when the cell duplicates its organelles Mitosis- when the cell splits into two daughter cells that have the same amount of DNA as the parent cell while it was in G1-A four-stage process that creates two identical cells from one original cell.

homologous chromosomes

Homologous chromosomes are chromosomes of the same size and similar structure. In their structure homologous chromosomes have the same genes as each other in the same sequence but do not necessarily have the same allele of those genes. two chromosomes, one of paternal origin, the other of maternal origin, that are identical in appearance and pair during meiosis

How Sister chromatids come apart in Mitosis.

In anaphase, the sister chromatids are drawn apart the opposite poles of the cell. After separation the sister chromatids are referred to as daughter chromoses.

Where does Meiosis occur in the body?

In males: testes In females: ovaries

How Sister chromatids come apart in Meiosis.

In meiosis, by contrast, the sister chromatids come apart in two steps—their arms have separated at anaphase I, while their centromeres remain attached, separating only at anaphase II

sexual life cycle

Involves genetic contribution from both parents. Provides much greater genetic variation within a species.

How CDK and cyclin concentrations correlate.

It is suggested that cyclins have a general function of spatially focusing Cdk activity and that in the plant cell the concentrations of cyclins are important mediators of CDK activity at the cytoskeleton, chromosomes, spindle, nuclear envelope, and phragmoplast.

What does meiosis produce?

It produces two diploid cells that are identical to each and parent cells

When does Meiosis occur in the body?

Meiosis occurs when a cell in your reproductive system replicates its DNA and splits first into two daughter cells, then into four gametes. The gametes, which are known as sperm cells in men and egg cells in women, each have only half the DNA of the original cell.

Differences between Mitosis and Meiosis.

Mitosis produces two cells from one parent using one division event. However, meiosis produces four new child cells with two divisions, each of which has half the genetic material of its parent. Mitosis takes place all over the body, while meiosis only takes place in the sex organs and produces sex cells.

Cell Cycle Control - how checkpoints work.

The cell cycle is controlled by three internal checkpoints that evaluate the condition of the genetic information. spindle checkpoint (M checkpoint) prevents separation of the duplicated chromosomes until each chromosome is properly attached to the spindle apparatus G2 checkpoint ensures all of the chromosomes have been replicated and that the replicated DNA is not damaged restriction point (G1 checkpoint) a point in the animal cell cycle at which the cell becomes "committed" to the cell cycle, which is determined by external factors and signals An important function of many checkpoints is to assess DNA damage, which is detected by sensor mechanisms. When damage is found, the checkpoint uses a signal mechanism either to stall the cell cycle until repairs are made or, if repairs cannot be made, to target the cell for destruction via apoptosis (effector mechanism).

How the cell cycle relates to cancer.

The cell cycle, the process by which cells progress and divide, lies at the heart of cancer. In normal cells, the cell cycle is controlled by a complex series of signaling pathways by which a cell grows, replicates its DNA and divides. This process also includes mechanisms to ensure errors are corrected, and if not, the cells commit suicide (apoptosis). In cancer, as a result of genetic mutations, this regulatory process malfunctions, resulting in uncontrolled cell proliferation.

mitotic spindle

The collective term for all the spindle fibers that form during mitosis. It is a spindle-shaped structure that develops outside the nucleus during mitosis. The fibers that constitute the mitotic spindle pull the chromatids apart toward opposite poles.

Genotype

The genetic constitution of an individual organism. investigate the genetic constitution of (an individual organism). (alleles/letters) bb

What is the goal of meiosis?

The goal of meiosis, however, is to produce sperm or eggs, also known as gametes. The resulting gametes are not genetically identical to the parent cell. Gametes are haploid cells, with only half the DNA present in the diploid parent cell.

sister chromatids

Two identical strands joined by a common centromere as a result of a chromosome that duplicated during the S phase of the cell cycle.

zygote

a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

Testcross

a genetic cross between a homozygous recessive individual and a corresponding suspected heterozygote to determine the genotype of the latter

kinetechore

a highly specialized structure that forms at centromeric chromatin during mitosis and meiosis to act as the chromosomal attachment site for the dynamic spindle microtubules that drive chromosome segregation.

dihybrid

a hybrid that is heterozygous for alleles of two different genes. two traits ex: (YyRr x YyRr)

monohybrid

a hybrid that is heterozygous with respect to a specified gene.

Chiasmata

a point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.

co-dominance

a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked. both alleles are expressed. ex: blood types or Rr=white with red spots

chromosomes

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Recessive Allele

an allele that produces its characteristic phenotype only when its paired allele is identical.

Dominant allele

an allele that produces the same phenotype whether its paired allele is identical or different

centrosomes

an organelle near the nucleus of a cell that contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division.

malignant tumor

cancerous and are made up of cells that grow out of control. Cells in these tumours can invade nearby tissues and spread to other parts of the body. Sometimes cells move away from the original (primary) cancer site and spread to other organs and bones where they can continue to grow and form another tumour at that site. This is known as metastasis or secondary cancer. Metastases keep the name of the original cancer location. e.g. pancreatic cancer that has spread to the liver is still called pancreatic cancer.

Homozygous

having identical pairs of genes for any given pair of hereditary characteristics having the two genes at corresponding loci on homologous chromosomes identical for one or more loci BB or bb

recombinant chromosomes

of or resulting from new combinations of genetic material a cell or organism whose genetic complement results from recombination. the genetic material produced when segments of DNA from different sources are joined to produce recombinant DNA.

Allele

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

incomplete dominance

refers to a genetic situation in which one allele does not completely dominate another allele, and therefore results in a new phenotype. looks like blending ex: RR= red rr=white Rr=pink

Heterozygous

refers to a pair of genes where one is dominant and one is recessive — they're different Bb (carrier)

metastasis

the development of secondary malignant growths at a distance from a primary site of cancer.

What is crossing over?

the exchange of genetic material between non-sister chromatids during synapsis of Prophase I of meiosis.

transformation

the genetic alteration of a cell by introduction of extraneous DNA, especially by a plasmid. the heritable modification of a cell from its normal state to a malignant state.

genome

the haploid set of chromosomes in a gamete or microorganism, or in each cell of a multicellular organism. the complete set of genes or genetic material present in a cell or organism.

chromatin

the material of which the chromosomes of organisms other than bacteria (i.e., eukaryotes) are composed. It consists of protein, RNA, and DNA.

trihybrid testcross

the mating of two individuals, organisms, or strains that have different gene pairs that determine three specific traits or in which three particular characteristics or gene loci are being followed.

karyotype

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

heredity

the passing on of physical or mental characteristics genetically from one generation to another.

centromeres

the point on a chromosome by which it is attached to a spindle fiber during cell division.

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment. what it looks like-blue eyes

genetics

the study of heredity and the variation of inherited characteristics. the genetic properties or features of an organism, characteristic, etc.