Genetics Exam One Study Guide

Front 1

Quantitative Interitance

Back 1

Polygenic inheritance

Front 2

Qualitative Inheritance

Back 2

Discreet Variation (one gene)

Front 3

Metacentric

Back 3

Centromere is in the middle

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Submetacentric

Back 4

Centromere is between middle and end

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Acrocentric

Back 5

Centromere is between middle and end but closer to the end

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Telocentric

Back 6

Centromere is at the end of the chromosome

Front 7

Mitosis

Back 7

Cell division used either for asexual reproduction or growth and repair of somatic cells

Front 8

Interphase

Back 8

Longest phase of cell cycle

Chromosomes are extended and uncoiled; chromatin forms

Front 9

Prophase

Back 9

First phase of mitosis:

Chromosomes coil up and condense; centrioles divide and move apart; the nuclear membrane breaks down

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Prometaphase

Back 10

Second phase of mitosis:

chromosomes are clear double structures; centrioles reach the opposite poles; spindle fibers form

Front 11

Metaphase

Back 11

Third phase of mitosis:

chromosomes align individually in the center of the cell; centromeres attach to the spindle fibers

Front 12

Anaphase

Back 12

Fourth form of mitosis:

centromeres split and daughter chromosomes begin to migrate to the opposite poles along the spindle fibers

Front 13

Telophase

Back 13

Final phase of mitosis:

daughter chromosomes arrive at opposite poles; cytokinesis begins; spindle fibers break down; nuclear membrane forms

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Cytokinesis

Back 14

the division of cytoplasm between the daughter cells

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Meiosis

Back 15

the process of gamete formation; involves two stages of division

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Meiosis I

Back 16

Reductional division (2N --> N)

Front 17

Meiosis II

Back 17

Equational division (N --> N)

Front 18

Chiasmata

Back 18

Evidence of crossing over

Front 19

Crossing over

Back 19

The reciprocal exchange of chromosomal segments between non-sister chromatids of a homologous pair

Front 20

Prophase I

Back 20

Longest stage of Meiosis; broken into 5 stages.

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Leptonema

Back 21

Chromosomes begin to condense; chromosomes appear beaded; homology search begins

Front 22

Zygonema

Back 22

Rough pairing of homologous chromosomes; condensation continues; synaptonemal complex begins to form between homologues

Front 23

Pachynema

Back 23

condensation continues; synaptonemal complex is complete; homologue pairing referred to a synapsis; tetrads exist; crossing over occurs between non-sister chromatid within pairs

Front 24

Diplonema

Back 24

condensation continues; synaptonemal complex breaks down; homologous chromosomes held together by chiasmata between non-sister chromatids

Front 25

Diakinesis

Back 25

chromosomes are condensed; homologous chromosomes held together by chiasmata; nuclear membrane breaks down; spindle fibers form; centromeres attach to the spindle fibers

Front 26

Metaphase I

Back 26

homologues are paired; one homologue of each pair orients itself towards a random pole (random orientation)

Front 27

Anaphase I

Back 27

one homologue from each pair moves to opposite poles; centromeres do not divide

Front 28

Telophase I

Back 28

homologues are at opposite poles; cell begins to divide; cytokinesis begins

Front 29

Interkinesis

Back 29

A pause between phases; no change to DNA occurs

Front 30

Meiosis II

Back 30

almost identical to mitosis; results in 4 genetically unique haploid gametes

Front 31

Heredity

Back 31

the process by which living organisms produce offspring that resemble their parents

Front 32

Blending Inheritance

Back 32

There is an apparent so of variation in every generation

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Mendel's Initial Steps

Back 33

1. Establish true-breeding lines

2. Cross two true-breeding line to produce hybrids

Front 34

Mendel's Observations

Back 34

1. Only one version of the trait appeared in F1 hybrid

2. The form not seen in the F1 hybrid is the recessive gene

3. In F2, both versions of the trait appear

4. In F2, the dominant trait appears ~3x the recessive trait

F2 contains 1 true-breeding dominant, 2 hybrids, and 1 true-breeding recessive

Front 35

Mendel's Hypothesis

Back 35

1. Each trait is determined by heredity factors

2. Heredity factors are transmitted from parent to child through gametes

3. Each heredity factor has alternate forms

4. An organism has two copies of the heredity trait for each trait, one from each parent

5. The two copies of the heredity factor remain distinct properties

6. The two copies of the heredity factor are distributed singly and in equal proportions into the gametes

7. Gametes unite at random during reproduction

Front 36

Monohybrid Cross

Back 36

Examines 1 gene

1:2:1 genotype ratios

3:1 phenotype ratios

Front 37

Test Cross

Back 37

Crossing an individual with a dominant phenotype but unknown genotype with an individual who is a true-breeding recessive.

Front 38

Dihybrid Cross

Back 38

Crossing 2 genes

9:3:3:1 phenotype ratio

Front 39

Dihybrid Test Cross

Back 39

If dominant: all show dominant phenotype

If hybrid: there is a 1:1:1:1 ratio of phenotypes

Front 40

Independent Assortment

Back 40

The segregation of the pairs of alleles for one trait occurs independently of the segregation of the alleles for the other trait during gamete formation

Front 41

Spermatogenesis

Back 41

The meiotic process by which sperm is created. It results in 4 sperm cells

Front 42

Oogenesis

Back 42

The meiotic process by which eggs are produced. It results in one ovum, with two polar bodies being formed along the way

Front 43

Polar Body

Back 43

A discarded cell that contains one of the nuclei of the division process, but almost no cytoplasm as a result of an unequal cytokinesis

Front 44

Probability

Back 44

1. The proportion of times that an event is expected to occur in repeated trials

2. Frequency of occurrence in a group

Front 45

Probability of an event in a single trial

Back 45

m/n

m: number of times that the event of interest occurs in n

n: number of equally likely outcomes

Front 46

Addition Rule

Back 46

P(A or B) = P(A) + P(B) - P(A and B)

if A and B are mutually exclusive, then P(A and B) = 0, but this only occurs when looking at one gene

Front 47

Conditional Probability

Back 47

The probability that event B occurs, given that A has already occurred

Front 48

Multiplication Rule:

Back 48

P(A and B) = P(A) X P(B, given A)

If two or more traits are independent, as in independent assortment, then A has no effect on B so P(A and B) = P(A) X P(B)

Front 49

Pedigree Analysis

Back 49

Deduce the qualitative trait by examining the segregation of alleles in several generations of related individuals

Front 50

Complete Dominance

Back 50

Phenotypically, the heterozygous individual looks identical to the homozygous dominant individual

Front 51

Partial (incomplete) Dominance

Back 51

Phenotypically, the heterozygous individual is between the two homozygous individuals, but looks more like one than the other

Front 52

No Dominance

(Additive Dominance)

Back 52

Phenotypically, the heterozygous individual is an exact intermediate of the two homozygotes

Front 53

Codominance

Back 53

Phenotypically, the heterozugous individual is an intermediate, but shows full expression of both alleles

Front 54

Multiple Alleles

Back 54

Three or more alleles for a particular gene exist in a population or species, but only two alleles can be present in an individual

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Lethal mutant Alleles

Back 55

The wild type gene product is needed in the correct amount for the survival of the organism

Front 56

Recessive lethal

Back 56

Homozygous recessive individuals die

Front 57

Dominant Lethal:

Back 57

Homozygous dominant and heterozygous individuals die due to possession of dominant allele

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Dominant morphology, but recessive lethal

Back 58

Homozygous recessive individuals die, but heterozygous individuals who a non-wild type morphology (ie. curly and antennapedia)

Front 59

Modified Monohybrid phenotype ratio

Back 59

No Dominance:

1/4 AA, 2/4 Aa, 1/4 aa

Front 60

Modified Dihybrid phenotype ratio

Back 60

1st gene shows complete dominance

2nd gene shows no dominance

Do branched out structure

Front 61

Epistasis

Back 61

1. The occurrence of novel phenotypes produced by the combined effects of two different genes on one trait

2. The genotype at one gene masks the effect or expression of the genotype at another different gene, where both genes affect the trait

Front 62

Recessive Epistasis

Back 62

If the individual is homozygous recessive at one gene, it masks the expression at the second gene

9:7 phenotype ratio

Front 63

Dominant Epistasis

Back 63

If the individual has at least one dominant allele at a gene, it masks the expression at the other gene

13:3 phenotype ratio

Front 64

Sex-Linked Traits (X-linked)

Back 64

Genes are actually on the X chromosome

Front 65

Sex-Associated patterns of inheritance

Back 65

Due to autosomal chromosomes, but linked with the gender of the individual

Front 66

Sex-Limited inheritance

Back 66

A trait that is expressed in only one sex even though the trait may not be X-linked

Front 67

Sex-Influenced Inheritance

Back 67

Phenotypic expression conditioned by the sex of the individual. A heterozygote may express one phenotype in one sex and an alternate phenotype in the other sex