Genetics test 1

Genetic is the study of? (2 things)

1.heredity, trait variation, & the molecular mechanisms underlying traits and heredity

2.biological functions of genes and their regulation, biotechnology and medicinal applications

what are transmission genetics?

how traits are inherited

what are Molecular genetics

cellular processes governing inheritance and expression of genetic information

what are Population genetics

the genetic composition of populations across geography and time

what is the Germplasm theroy

Every cell contains a complete set of genetic information

what does the germline cells do?

give rise to gametes which carry the genetic information during

reproduction

do somatic cells contirbute?

No

what is a Gene

a functional unit of heredity encoded in DNA

what are prokaryotes

cells that usually have only one circular chromosome, Dna is not bound by the nucleus

what are Eukaryotes

tend to have many linear chromosomes, DNA is contained within the nucleus

what is DNA packaged as in Eukaryotes?

Chromatin

what are Nucleosomes made up of?

DNA coiled around histone protein complexes, along with other structural proteins

what are viruses consisted of

Viruses are consisted of a capsid containing

genetic material (Which can be either DNA or RNA)

what is and origin of replication

where Duplication of the genetic material begins from, serves as a tether point drawn to opposite sides of the cell

what is bianary fission

the separation of the duplicated genome between the daughter cells

What is Ploidy?

the number of distinct copies of each chromosome

what does it mean if an animal is diploid?

they have two copies of each chromosome as a homologous pair (except sex chromosomes)

what does it mean if a eukaryote is Haplid

have one copy of each chromosome for most of their life cycle

What is a polyploid

having more than two copies of chromosomes (common in plants but rare in animals)

what are alleles

Versions of a gene with different DNA sequences and associated with distinct phenotypes

what is a chromosome made up of

made up of two arms with a centromere (central

organizational domain) between

Telomeres are found at the ends

It may exist as a single chromatid or a

pair of sister chromatids depending on

the point in the cell cycle

what are telomeres

the stable end of the chromosome

what is a centromere

a constricted region where the kinetochores form and the spindle microtubules attach

what is the first step of the cell cycle

G1 where the cell grows

what is the second step of the cell cycle

G0 if a cell enters a non dividing phase

what is the third step in the cell cycle

after the G1/S CHeckpoint, the cell is committed to dividing

what is the 4th step in the cell cycle

S phase, Dna duplicates

what is the 5th step in the cell cycle

G2, the cell prepares for mitosis

what is the 6th step in the cell cycle

after the G2/M checkpoint, the cell can divide

What is the 7th step in the cell cycle

M phase, where mitosis and cytokinesis

what is m phase

where nuclear and cellular division occur

what is interphase

where cell growth happens

what happens in prophase

chromosomes condesne, each chromosome posseses two chromatids. the mitotic spindle forms

what happens in prometaphase

the nuclear membrane disintegrates. spindle microtubles attach to chromatids

what happens in metaphase

chromosomes line up on the metaphase plate

what happens in anaphase

Sister chromatids separate and move toward opposite poles

what happens in telophase

chromosomes arrive at the spindle poles. the nulcear membrane re-forms and the chromosomes relax

what happens in cytokinesis

the cytoplasm divides. Cell wall forms in plant cells

what does Meiosis do

generates gametes from germ cells,Starting from a diploid (2n) cell with replicated

chromosomes, two successive divisions result in

haploid (n) gametes with a single copy of each

chromosome

what type of reproducion is Meiosis associated to

sexual reproduction and greatly increases genetic diversity within populations

middle prophase 1

chromosomes begin to condense and the spindle forms

late prophase 1

homologus chromosomes pair and crossing over takes place. the nuclear membrane breaks down

metaphase 1

homologus pairs of chromosomes line up along the metaphase plate

anaphase 1

homologus chromosomes seperate and move toward opposite poles

telophase 1

chromosomes arrive at the spindle poles and the cytoplasm divides

Prophase 2

the chromosomes recondence

Metaphase 2

Individual chromosomes line up on the equatorial plate

anaphase 2

sister chromatids separate and move toward opposite poles

Telophase 2

chromosomes arrive at the spindle poles, and the cytoplasm divides

reduction division

in Metaphase I and Anaphase I, the homologous pairs line up on the metaphase plate and then migrate to poles (instead of sister chromatids separating as in Mitosis)

Equatorial division

In Meiosis II, the sister chromatids now line up at the metaphase plate during Metphase II and separate during Anaphase II

how to calculate the number of possible gametic outcomes in meiosis

The number of possible gametic outcomes is 2n where n = number of chromosomes. For humans this is 223, or 8,388,608 possible combinations

what is recombination

The exchange of chromosomal segments between homologous

chromosomes

who was Gregor Mendel

Augustinian friar and botanist

what was the “Experiments on Plant Hybridization” (1866)

established the first principles of heredity. went largely without notice until the end of the century when new work regarding the basis of inheritance began

what was the “Experiments on Plant Hybridization” (1866) studying?

This pioneering work was done with pea plants, Pisum sativum .He focused on seven traits for which there were true-breeding varieties in their collection

what are genes

An Inherited factor(encoded in DNA) that helps determine a characteristic

what is a locus

a specific place on a chromosome occupied by an allele

what is a genotype

a set of alleles possessed by an individual organism

what is a homozygote

an individual organism possessing two of the same alleles at a locus

what is a heterozygote

an individual organism possessing two different alleles at a locus

what is a characteristic or character

an attribute or feature possessed by an organism

what is a Phenotype or trait

the appearance or manifestation of a characteristic

what is a monohybrid cross

Cross-fertilization of two varieties that differ in one trait. Done as a reciprocal cross (with pollen donors of the opposite trait in both directions)

P(parental) generation for the pea experiment

crossing homozygous lines for round seeds and wrinkled seeds

F1(first filial) generation in the pea experiment

in this generation, all plants are heterozygous but have the round seed phenotype

F2 (second filial) generation in pea experiment

in this generation, a mixture of genotypes is present, and the round seed and wrinkled seed phenotypes are present in a 3:1 ratio

Segregation(Mendels first law)

1. Each individual organism possess two alleles encoding a trait

2. alleles separate when gametes are formed

3. alleles separate in equal portions

what is a Dihybrid cross

Cross-fertilization of two varieties that differ in two true-breeding traits in the parental generation

what is Independent assortment(mendels second law)

Alleles at different loci sperate independantly

Branch diagram

A branch diagram can help breakdown probability of genotypes and phenotypes for a dihybrid cross

With independent assortment, the probabilities follow from two monohybrid crosses

what is chi square and its equation

Determine whether to reject a null hypothesis that differences in observed vs. expected outcome are due to chance

Based on a table of probabilities of observing a χ2 value

The equation uses the Observed and Expected values:

Larger values are more unlikely than smaller value

Eukaryote life cycle

Diploid zygote goes to halpoid gamete through meiosis and the undergoes fertilization to become another diploid zygote.

how does xy sex determination work?

the female parent contributes one of two possible X chromosomes, while the male parent provides either an X or Y chromosome\

This generates a 1:1 ratio of sexes but four different possible combinations chromosomes

male vs female genetic types during sex determination

the male is heterogametic, as the gametes produced can either contain X or Y chromosomes

The female, by contrast, is homogametic

types of syndromes in sex chromosomes

Turner: XO, Klinefelter: XXY,XXYY,Etc., Triple-X: XXX, Poly X Female, XXXX

whats differernt about the x and y chromosomes

they are not homologus

what do pseudoautosomal regions do?

guide paring during meiosis

whats is the sex-determining region Y gene (SRY) do

is responsible for developmental of biological males in most mammals

what was found out from the fly experiment in sex determination

The Y chromosome does not directly determine sex but rather the ratio of X chromosome to autosomes

why was the fly experiment so important?

X-linked inheritance of a trait was the first experimental evidence that the

chromosomes carried genes

what is the nondisjunction theroy?

in nondisjunction, chromosomes fail to separate correctly during meiosis

Nondisjunction theory explains the novel progeny which normally should not be possible if the white- eyed female was XwXw – all females from the red- eyed male cross should in that case be X+Xw and all males XwY

The XwXwY female can now produce a Y gamete, combining with the male to produce X+Y progeny, or a XwXw gamete, combining with the male to produce another XwXwY female

what is X inactivation

In 1961 Mary Lyon proposed that the theory of X-inactivation – in individuals with two X chromosomes, one is randomly inactivated and maintained in a tightly compacted inaccessible (mostly) form

This is presumed to act as a form of dosage compensation

what is The tortoiseshell pattern in cats an example of

X-inactivation

The orange color gene is X-linked, so males can be orange or black.

Heterozygous females are tortoiseshell as some cells inactivate the X

chromosome with the orange gene.

Complete dominance patterns are?

one allele in in a heterozygote is solely responsible for the phenotype

what is incomplete dominance

the heterozygote is intermediate between the phenotypes of homozygous parents

Codominance

is also very common at the molecular level

both alleles with differing functions are expressed

example: the two types are encoded by alleles of a gene, LM or LN

Individuals with heterozygous LMLN genotype have both antigens on their

blood cells

What is the pentrance of an allele

in not fully penetrant alleles, a portion of individuals with the allele have

no obvious phenotype. the genotype has a chance to not affect the phenotype

lethal alleles

the genotype made is lethal to the embryo

mutiple allele systems

IA encodes for the A antigen

IB encodes for the B antigen

i encodes for no antigen

The IA and IB alleles are codominant,

while both being dominant to i

Therefore type A, type B, type AB and

type O blood types are all observed

what is an example of two genes contributing to a trait

• In skin color for red bell pepper, two dominant Y+ and C+ alleles contribute, yy cc individuals have a cream color

• The heterozygous progeny will be red, following a dominance pattern

• Individuals with cc genotype and at least one Y+ allele are peach color

• Individuals with yy genotype and at least one C+ allele are orange

• This is a 9:3:3:1 ratio for the dihybrid cross but with 4 phenotypes of one trait

epistasis definition

one gene has an effect that masks the effect of another gene

hypostatic gene

the gene that is being masked

epistatic gene

the gene that masks the other gene

recessive epistasis

the recesive alleles Ex. ee are the epistatic gene

dominatn epistasis

Ex. a dominant allele at the W locus inhibits production of a

green pigment compound

Duplicate recessive epistasis

two different loci are both independently required for a trait (here, pigmentation in snails)

complementation

occurs when independent

loci are crossed.