LS7B Midterm 1 Meiosis and Genetics

how many physical copies of TRPV4 gene are present in each gamete?

1

whats recombination frequency of independent assortment

50

Allele

Different forms of a gene

T or F: Somatic mutations are important to the evolutionary process; most cancers result from somatic mutations.

F

When the F1 plants are allowed to self fertilize, they produced both yellow and green peas in the next generation. How is this explained?

In the F1 heterozygotes, the alleles segregate from each other when gametes form and then combine to make homozygotes and heterozygotes offspring.

what happens in meiosis II

Meiosis II is like mitosis; sister chromatids separate and four haploid cells are formed. Note that each has half the chromosomes of the parent cell. These cells differ genetically from each other and from the cells of the parents.

How do mutations arise?

Mutations arise randomly and independent of other mutations in the cell.

The gene for nose shape is found on the X chromosome. Round nose is dominant to pointed nose. Human individuals with XXY (an additional X chromosome) are designated male. Individuals with XO (only one X chromosome) are designated female. Identify the possible nondisjunction events (rare mistakes during meiosis) that could explain the phenotype of the offspring. An XY parent with a round nose and a XX parent with a round nose have an offspring with Klinefelter Syndrome (genotype XXY) with a pointed nose.

Nondisjunction could have occurred in meiosis 2 of the XX parent.

incomplete penetrance

Not all individuals with a mutant genotype show the mutant phenotype. Penetrance is proportion of ppl w genotype that show expected phenotype. if less than 100 than incomplete

DO PEDIGREE PROBLMES LPLS

OK

independent assortment

One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes; doesn't dependon other genes

anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

Define the terms SNP, VNTR, RFLP, and genetic marker

SNP (single-nucleotide polymorphism) - A site in the genome where the base pair that is present differs among individuals in a populationSNP started as a point mutation → over time became genetic basis for another alleleGenetic marker - gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species vntr: Cut DNA with enzyme and can tell if DNA has correct sequence depending on size + number of sizesCan compare to see how many times enzyme cuts RFLP: cut dna to separate fragments by size

what are three types of genetic markers

SNP , RFLPs, VNTR

Settings:Mode of inheritance - Recessive Parental generation -Male - Heterozygous Female - Homozygous mutant Matings between relatives - disallow Progeny in first generation - 4S how carriers - turn on Why is there a higher number of carriers than affected individuals?

Since both parents have disease alleles, all the offspring will inherit at least one mutant allele.

Calculate genetic map distances among linked genes from the frequencies of progeny with recombinant phenotypes, and construct a genetic map from data provided

Since genes are linked, can calculate genetic distance between two genes, find the recombination frequency by adding the recombinant DNA, and use this information to construct a genetic mappercent recombinant= (number of recombinants/total number of progeny)*100value of percentage of recombinants is usually converted directly into map units (mu)

incomplete dominance

Situation in which one allele is not completely dominant over another allele

incomplete dominance

Situation in which one allele is not completely dominant over another allele. Heterozygous genotype is intermediate b/w those of homozygous genotypes ex) RR red, rr white, Rr pink

pleiotropy

The ability of a single gene to have multiple effects on 2+ seemingly unrelated phenotypic traits

The use of the multiplication rule requires which option?

The events being considered occur independently.

In this partial image of anaphase I of meiosis, most of a chromosome is shaded dark, whereas a portion of what is in the circle is shaded light. Which of the statements best explains the meaning of this shading?

The light part came from the homolog by crossing over.

heritability

The proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied.

sing the given settings, press "Generate Pedigree" (NOT "Generate Random Pedigree") three to six times, and notice the frequency of affected sons and daughters in the F1 to F4 progeny. Settings:Mode of inheritance - X-linked recessive Parental generation -Male - Nonmutant Female - Heterozygous Matings between relatives - disallow Progeny in first generation - 4 Show carriers - turn on Why aren't there any affected females in the F1 generation under these conditions?

There is only one affected allele segregating in the pedigree.

When p53 becomes mutant in cells already mutant for APC and Ras, what occurs?

These cells survive despite DNA damage and divide extremely rapidly.

Interpret the results of crosses and pedigrees whose results differ from Mendelian expectations because of incomplete dominance, epistasis, or hierarchy of dominance

They will be affected but will not show the dominant trait fully

Relate trait values of offspring to parents to identify heritability of traits

To determine heritability, compare the best fit line of mid-parent to mid-offspring (mean) trait

The addition rule requires which option?

Two outcomes (such as having the genotype BB or Bb) are mutually exclusive in an organism.

multiplication rule

When outcomes can occur simultaneously and the occurrence of one has no effect on the likelihood of the other, we multiply their individual probabilities. "and". Independent of each other

Create a pedigree from a scenario

X-recessive=show criss crossrecessive=might have mom and dad not affected but offspring affecteddominant=mostly all affected

variable expressivity

a particular phenotype is expressed with a different degree of severity in different individuals

genotype by environment interaction

a phenotype is the result of an interplay between genes and the environment

addition rule

addition: when possible outcomes considered can't happen @ same time (either/or), you add probabilities. Different orders too.

Which of the answer choices is a possible human genotype that could result from nondisjunction of the sex chromosomes in one of the parental gametes? A) XO B) All of these choices are correct C) .XXX D)XYY E) XXY

b

Which of the statements is least likely to produce recombinant chromosomes? A) crossovers between non-sister chromatids B) crossovers between sister chromatids C) crossovers between homologous chromosomes

b

Which of the statements are true of both first- and second-division nondisjunction? Select all that apply. A) Half of the gametes produced are wild-type, whereas half are mutated. B) Gametes are produced with extra chromosomes. C) Sister chromatids fail to separate. D) Homologous chromosomes fail to separate. E) Gametes are produced with missing chromosomes.

b and e

genetic variation

based on copy of the allele for that gene

In a homozygous genotype:

both alleles for a given trait are the same.

vntr

diff # repeated sequence. can vary. if polymorphism no match than def not it, need 6-8 places to make sure tho

what does mean when trait is dominant or recessive/

dominant is trait appear in F1 gen, recessive no appear in F1 gen? Diploid; only 1 copy of gene needed to carry out normal fuction

Which of the statements is true about gametes? A) They are found in animals but not plants. B) They are genetically identical to other gametes formed during meiosis. C) They have the same number of chromosomes as a somatic cell of the same individual. D) They are formed by mitotic cell division. E) They fuse to form a new organism during fertilization.

e

higher norm of reactions show

environment has noticeable effect on phenotype

if breed homo straight ear cat w homo folded ear cat and offspring all folded ear, what does that tell u?

folded ear is dominant

If mutations occur at random with respect to an organism's needs, how does a species become more adapted to its environment over time?

good mutations increase chance of survival and reproduction, so species become more adapted over time.

whats norm of rxn?

graphically depicts how phenotype changes depending on environment

A normal female who carries a recessive X-linked allele for hemophilia will pass it on to:

half both sons and daughters

What is an example of a complex trait?

height, weight

how can you tell if its a heritable trait

if it has a positive correlation

hiearchy of dominance

its when many alleles for a single gene

A mutation with a deleterious effect on the function of a protein encoded by a human mitochondrial gene will be:

maternally inherited

how r snps related to mutations and alleles?

may b linked; if linked can be used as genetic marker

what does the frequency of crossing over represent

measure of genetic distance b/w 2 genes; % is equal to map unit NOT kB

how do genes and environment effect be measured?

measured in effect on variation of phenotypes of individuals in a pop

A male baby is born with the sex-chromosome constitution XYY. Both parents have normal sex chromosomes (XY in the father, XX in the mother). In which meiotic division of which parent did the nondisjunction take place that produced the XYY baby?

meiosis 2 nondisjunction in father.

Homologous chromosomes separate from each other in:

meiosis I

what is mitosis similar to?

meiosis II

a mutation that changes one amino acid into another is called a

missense mutation

describe how to use snp

more snp observed near disease genes mean may be associated

The definition of mutation is "any heritable change in the genetic material." The qualifier "heritable" is necessary because:

most changes in the genetic material are repaired soon after they occur.

genetic risk factor is

mutation that inc risk of disease in individual

How can mitochondrial DNA data be used to trace ancestry

no recombination, inherit maternally, mutation build up, separate from other lineage

When heritability is 0%, genes play:

no role in variation in the trait among individuals.

does snp always point to disease?

no, b/w unaffaected and disease individuals dont always point, if exon missing protein code can be altered and alter phenotype

do people inherit cancer?

no, cancer is result of multiple somatic mutations, also influenced by the environment

can crossing over always cause recombination?

no, if the genes r close together and don't get separated not recombinant b/w those two genes

Does regression toward the mean imply that the human population is getting shorter over time?

no, j that extreme phenotypes tend to have more avg offsrping

is relationship b/w genotype and phenotype always the same?

no: variable expressivity, incomplete dominance. environment interact w/ genes change phenotypes/ same traits show diff phenotypes for same genotype, same genotype show diff phenotypes.

Sometimes homologous chromosomes fail to separate normally during meiosis I, a process called:

nondisjunctino

In which type of nondisjunction could the two copies of a chromosome in a gamete be heterozygous?

nondisjunction in the first meiotic division

What nondisjunction/fertilization events can lead to XXy

nondisjunction meiosis I male, I and II female

how is heritability misinterpreted

nonscientifficaly implies capability of being herited/passed by inheritance; suggest heritability has something to do w/ inheritance of trait. but only on variation

During meiosis crossing over takes place between:

nonsister chromatids

sporadic mutation

not present in all cells so not passed on to offspring

whats the slope of regression line

of progeny mean against parental mean to estimate heritability

What is "regression toward the mean" and why does it occur for complex traits?

offspring exhibit avg phenotype less diff from populatin than their parents. bc segregation and recombination break genes, also bc enviornmetnal factors

what does regression towards mean mean?

offspring exhibit avg phenotype thats intermediate b/w that o fparents and of pop as a whole.

look at peq recessive small pedigree problem ok

ok

practice big punnett square problems

ok

study epistasis exapmle

ok

study pedigree problems and probabilities

ok

study recombination problems

ok

study rflp cutting genetic markers

ok

study snp levels in regards to linkage to a disease

ok

STUDY ALEX AND ANNA PROBLEM

okie

whats translocation

part of 1 chromosomes transfer to nonhomologous chromosome or new site on same chromosome

criss cross inheritence in x linked genes?

pass on to daughter, to son, to daughter

During which phase of meiosis do homologous chromosomes synapse with crossing-over between homologous chromosomes?

prophase I

4 phases of meiosis

prophase, metaphase, anaphase, telophase PMAT

What is the heritability of a trait and why does the heritability of a given trait depend on the population being studied?

proportion of tot variance due to genetics among indiviuals. bc of environment influence and diff genotypes in diff pops

How can you predict the genotypes and phenotypes of offspring if you know the genotypes of the parents?

punnett square and mendel's laws

Calculate the probability of a particular gamete being produced from an individual, assuming independent segregation of alleles

punnett squre

how does independent assortment relate to meiosis

random alignemnt in anaphase 1 of maternal and paternal chromosomes

whats example of cultural transmision

rich to rich like in humans

Determine if and where homologous recombination has occurred based on combinations of linked alleles

see if alleles are still linked; if separated, recombination has occurred

What are Mendel's two laws

segregation and independent assortment.

What two processes during meiosis result in genetically unique daughter cells

segregation, random alignment of chromosomes on metaphase plate; randomly receive maternal and paternal homologs

sry gene

sex determining region of the Y chromosome; if present is male, if not is female

why can multihybrid traits be put on punnett square?

small # genes, environment effect is minor, independent assormtnet for each of the 3 genes

Principle of Independent Assortment

states that genes for different traits can segregate independently during the formation of gametes; each pair of alleles segregates independently into gametes and doesnt affect that for other alleles

t or f: A Punnett square can be used to interpret the results of a testcross.

t

t or f: A complex trait can be influenced by the environment.

t

t or f: Genetic variations in DNA sequences in human populations, such as single nucleotide polymorphisms (SNPs), have been used to map "disease genes" by determining whether the SNP is linked to the mutant gene.

t

t or f: Homologous chromosomes usually have the same arrangement of genes along their length.

t

t or f: The tips of the arms of the X and Y chromosomes share small regions of homology. Genes located in these regions are inherited in the same manner as the ones found in autosomes.

t

t or f: dna must be replicated in order for cells to undergo meiosis

t

t or f; Without the SRY gene, humans and other mammals would develop and retain the female sex organs and phenotype.

t

t or f: Two genes, A and B, are found on the same chromosome. One chromosome has alleles A and B, while its homolog has alleles a and b. If genes A and B are so closely linked that the recombination frequency is 0 percent, only AB and ab gametes will be produced during meiosis.

t, If two genes are physically located very close to each other on the chromosome, then recombination cannot occur and only non-recombinant gametes will be produced.

t or f: A doctor is presented with a patient complaining of persistent muscle weakness. The patient mentions this is something that all of her children also experience, as did her mother when she was alive. This family may be suffering from a mitochondrial disease.

t, Mitochondria are the site of ATP synthesis, and thus provide the chemical energy necessary for many cellular processes including muscular contraction.

Genes that are close together in the same chromosome:

tend tobe transmitted together

nondisjuction

the failure of chromosomes to separate during meiosis. can occur during meiosis and mitosis

The principle of independent assortment holds that:

the pattern of inheritance of one trait does not influence the pattern of inheritance of another trait.

In Mendel's crosses:

the plants he started with had two alleles of each gene

phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

what does 0% heritability mean

variation is not due to genetics; only enviornment

whats 100% heritability

variation not due any part of environment

effects of mutation depends on

whether mutation is homo or heterozygous, and also environment

Among the progeny of a heterozygous round (Aa) x homozygous wrinkled (aa) testcross, three seeds are chosen at random. What is the probability that all three seeds are round?

(1/2)^3 There is a 1/2 chance that each seed is round. The probability of seed 1 AND seed 2 AND seed 3 all being round is found with the multiplication rule

A newly discovered strain of Anopheles gambiae, a mosquito, is found to be resistant to a particular insecticide due to a new allele at a specific locus. When individuals of this strain are mated with individuals of an insecticide-susceptible strain of A. gambiae, all offspring are susceptible. If males and females of these susceptible offspring are then mated with one another, what proportion of offspring do you expect will be resistant?

.25

Imagine an instance where there are two parents, and both have polydactyly (i.e., six fingers on each hand), a trait which is determined in this example by a single gene. They have four children, none of whom have polydactyly. What is the probability their next child will have polydactyly?

.75

A man affected with a mitochondrial disease mates with a woman who does not have a mitochondrial disease. What is the probability that their offspring will be affected?

0

in humans, how many pairs of homologous chromsomes are present in a single cella t the end of meiosis II?

0

Color blindness is a recessive X-linked trait in humans. In a family where the mother is color-blind and the father is normal, the probability of their having a color-blind son is:

1

How is meiosis different from mitosis?

1. Meiosis produces 4 new offspring cells, each w/ 1 set of chromosomes-thus 1/2 the # of chromosomes as the parent cell. Mitosis produces 2 offspring cells, each w/ the same # of chromosomes as the parents cells 4. meiosis is haploid daughter cells, mitosis is diploid 3. meiosis has 2 rounds of cell division. 2. Meiosis involves the exchange of genetic material b/w homologous chromosomes (crossing over)

Describe Mendel's principle of segregation and principle of independent assortment

1.. The principle of segregation states that individuals inherit two copies (alleles) of each gene, one from the mother and one from the father, and when the individual forms reproductive cells, the two copies separate (segregate) equally in the eggs or sperm.2. The principle of independent assortment states that the two copies of each gene segregate into gametes independently of the two copies of another gene.

Organisms with the genotypes AaBBCcDdEeff and AaBBCcddEeff are crossed. Assuming independent segregation and complete dominance for each trait, what is the expected proportion of the progeny that will be homozygous for all of the genes?

1/16

Given equal probabilities of the birth of an XY offspring or an XX offspring, what is the probability that a group of four siblings includes all XY offspring? All XX offspring? All XY offspring or all XX offspring?

1/16; 1/16; 1/8 In the mating of an XX female and XY male, 1/2 the offspring will be male and 1/2 will be female. The probability of all boys is (1/2)4, the probability of all girls is the same. The probability of all boys or all girls is the sum of these probabilities: 1/16 + 1/16 = 1/8.

Color blindness is a recessive X-linked trait in humans. In a family where the mother is heterozygous for color blindness and the father is color-blind, the probability of their having a color-blind daughter is:

1/2

if 2 ppl mate and have 2 children, prob 1 girl and 1 boy?

1/2

if 2 ppl mate and have a child, prob its a girL?

1/2

Alex and Anna are two people who are considering having children together. Alex, his father (XY parent), and his mother (XX parent) all have blood type B. His younger XX siblings and his XY siblings have blood type O. Anna, her XX parent, and her younger XY sibling all have blood type A. Anna's XX sibling and older XY sibling both have blood type O. Anna's XY parent has type B. What is the probability that Alex and Anna's first offspring will have blood type AB?

1/3

if know person is unaffected, is chance of AA 1/4 or 1/3?

1/3!!

if 2 ppl mate and have 2 children, prob girl first then boy?

1/4

For most genes on the human X chromosome, what percent of XY males with a mutant allele on the X chromosome will express the mutant phenotype?

100

If all variation among individuals in a population is due to differing genotypes alone, heritability is _____, and the slope of the line used to measure it is _____.

100%, 1

In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, A- means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect the shape of the seed capsule in the broadleaf weed known as shepherd's purse. Each gene has two alleles, one of which is dominant for the shape of the seed capsule. Genotypes of the form A- B-, A- bb, and aa B- have triangular seed capsules, whereas the seed capsules of aa bb genotypes are ovoid. What ratio of triangular : ovoid is expected from the cross Aa Bb x Aa Bb?

15:1 Only the double homozygotes would be ovoid

A true-breeding black rabbit is crossed with a true-breeding white rabbit to produce an F1 generation of 16 individuals. If the black color trait is dominant, which of the outcomes represents the expected phenotype of an F1 generation cross?

16 black rabbits, 0 white rabbits, 0 gray rabbits

if cross over happens, how many recombinant gametes?

2 bc only in between inner sis chromatids. most is 50%

if cell has diploid number 6 before meiosis, how many chromosomes in each gamete if meiosis II nondisjunction?

2 gamete w/ 3, 1 gamete w/ 4, 1 gamete w/ 2

In first division nondisjunction, how many gametes have extra and missing chromosome?

2 gametes have extra, 2 gametes have missing

if cell has 1 mutant copy and 1 wild type copy of gene, how many gametes have which one?

2 gametes have mut, 2 gametes have wt

if cell has diploid number 6 before meiosis, how many chromosomes in each gamete if meiosis I nondisjunction?

2 gametes w/ 4, 2 gametes w/ 2

what hypothesis regarding cancer

2 hit hypothesis, so basically if you inherit it your one step closer

in second division nondisjunction how many gametes have extra and missing chromosome?

2 normal, 1 extra, 1 missing

In the F2 generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, two seeds are chosen at random. What is the probability that one is round and the other is wrinkled?

2 × (3/4) × (1/4)

how many chromosomes in general in gametes in meiosis nondisjunction I?

2(n+1), 2(n-1)

Consider a gene with four alleles: A1, A2, A3, and A4. In the cross A1A2 × A3A3, how many offspring genotypes are possible?

2, The A3 allele from the second parent could combine with either the A1 or A2 allele from the first parent.

how many chromosomes in each cell at end of meiosis I

23

imagine non disjunction occurs in chromsome 14 in a human during meiosis II. what would be number of chromoomse in reultant gametes?

23 23 22 24

Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant's chromosomes occurs in meiosis II, the resulting sperm are expected to have the chromosome complement:

28, 28, 29, 27. Elephants have a diploid chromosome number of 28. Nondisjunction in the second meiotic division would produce some normal gametes and some aneuploid gametes, with either one extra chromosome or one too few.

Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant's chromosomes occurs in meiosis I, the resulting sperm are expected to have the chromosome complement:

29, 29, 27, 27. Elephants have a diploid chromosome number of 28. Nondisjunction in the first meiotic division would produce only aneuploid gametes with either one extra chromosome or one too few.

how many chromosomes in general in gametes in meiosis nondisjunction II?

2n, (n+1), (n-1)

In a cross between two individuals who are heterozygous for two traits determined by dominant and recessive alleles (Aa Bb), what is the expected ratio of offspring for the trait determined by the first gene (Aa)?

3:1

If nondisjunction occurs in the first meiotic division, how many of the four possible gametes produced from meiosis will have the wrong number of chromosomes?

4

how many physical copies of trpv4 gene present in metaphase I

4

dihybrid cross lead to what diff types

4 diff phenotypes and 9 possible genotypes

meiosis produces

4 haploid gametes

Consider a gene with four alleles: A1, A2, A3, and A4. In the cross A1A2 x A3A4, how many offspring genotypes are possible?

4, The A1 allele from the first parent could combine with A3 or A4 from the second parent for two combinations. The A2 allele from the first parent could combine with A3 or A4 for two more combinations for a total of 4.

The maximum frequency of recombination between two genes is:

50%

if two parents are heterozygous, and cross, how many have hetero genotype?

50%

what is the recombination frequency of independent assortment

50%

For two genes that show independent assortment, what is the frequency of recombination?

50%; 1/2 is Ab and 1/2 is aB recombinant if its ABab genotype gametes

What is the probability that any two seeds are green and two seeds are yellow in a pea pod with exactly four seeds?

54/256 or 21%. 1/4 prob green x 1/4 x 3/4 prob yellow x 3/4= 9/256. since 6 diff formations, multiply 9 by 256. aka add 6 times.

Consider a gene with four alleles: A1, A2, A3, and A4. How many distinct heterozygous genotypes are possible?

6 In this problem only consider the unique heterozygotes: there are six possible unique combinations.

whats the standard heritability determined?

60% variatin due to gene, 40% environemnt

If 2 heterozygous individuals crossed and dominant is folded ear, how many offspring folded ear?

75%

In a human cell at the end of prophase I, how many chromatids, centromeres, and bivalents are present?

92 chromatids, 46 centromeres, 23 bivalents

In a cross between two individuals who are heterozygous for two traits determined by dominant and recessive alleles (Aa Bb), what is the expected ratio of phenotypes for the traits determined by both genes?

9:3:3:1

phenotypic ratio of 2 heterozygous genes

9:3:3:1

quantitative trait

A complex trait in which the phenotype is measured along a continuum with only small intervals between similar individuals.

ABO blood type groups

A is AA or Ai, B is BB or Bi, AB is AB, O is ii

gene

A segment of DNA on a chromosome that codes for a specific trait

locus

A specific place along the length of a chromosome where a given gene is located.

inbred line

A true-breeding, homozygous strain. variation due only to environment

epistasis

A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited. often gene codes for proteins that act in same biochemical pathway affect ratio of phenotype; 2+ gene affect same trait

Mutations arise in which order in the colon cancer example shown in the animation?

APC, Ras, p53

Define the addition (i.e., sum) rule and the multiplication (i.e., product) rule

Addition rule (OR) this is used when results are mutually exclusive. nonspecific order, just give birth to one boy and one girl Multiplication rule (AND) is used when results are independent from each other. Order matters, first girl and then boy

Define the addition(i.e.,sum) rule and the multiplication (i.e., product) rule

Addition rule (OR) this is used when results are mutually exclusive. nonspecific order, just give birth to one boy and one girl Multiplication rule (AND) is used when results are independent from each other. Order matters, first girl and then boy

Refer to Simulation: Pedigree. Using the given settings, press "Generate Pedigree" three to six times, and notice the frequency of affected sons and daughters in the F1 to F4 progeny. Settings:Mode of inheritance - Recessive Parental generation -Male - Homozygous mutant Female - Homozygous mutant Matings between relatives - disallow Progeny in first generation - 4 Show carriers - turn off Why are all the offspring in the F1 generation affected?

All gametes produced that combine to make up the F1 generation have the mutant allele. It is impossible to have a carrier in the F1 generation.

heterozygous

An organism that has two different alleles for a trait

homozygous

An organism that has two identical alleles for a trait

genotype

An organism's genetic makeup, or allele combinations.

in what phase does segregation occur?

Anaphase I and Anaphase II

At which phase(s) in your meiosis diagram does assortment of genes take place?

Assortment of genes takes place during metaphase 1/anaphase 1. Independent assortment refers to how genes sort independently of each other, and during metaphase 1 the maternal and paternal chromosomes line up randomly in the middle of the cell; there is no specific way to line up, and the random alignment of maternal and paternal chromosomes on different sides of the metaphase plate creates different combination of alleles in gametes. If there is no crossing over, like in the diagram, independent assortment of genes doesn't affect the gametes at metaphase 2 because then each sister chromatid is identical, and so some of the resulting gametes have identical alleles. If there is crossing over, the random alignment of chromosomes along the metaphase plate will affect the resulting allele combinations in the gametes.

The mitochondrial DNA sequences of a large extended family were analyzed and compared to a single male in the family. Which of the relatives' mitochondrial DNA should be a match to this person? A) his children B) his sister's son C) .his brother's daughter D) his maternal grandfather E)his paternal grandmother

B, Mitochondrial DNA are passed from the mother to offspring. A male in the family will share the same mtDNA as his sister, and the sister would have passed on the same mtDNA to her son

Sunlight exposure has stronger effect on skin cancer risk in fair-skinned humans than in individuals with darker skin. This could be an example of: A) epistasis. B) pleiotropy. C) All of these choices are correct. D).genotype-by-environment interaction. E)differences in the norm of reaction.

C) All of these choices are correct. Skin color is affected by multiple genes that interact in different ways depending on the environment. All of these answer choices have an effect on the response an individual may have based on the genotype they have at multiple loci dictating skin color.

Flower color in snapdragons is due to a gene with incomplete dominance: CRCR plants have red flowers, CRCW have pink flowers, and CWCW plants have white flowers. Which cross is expected to yield progeny that all have pink flowers?

CRCR x CWCW Mating a homozygous red strain to a homozygous white strain would produce only pink offspring

Evaluate whether a specific SNP or VNTR is associated with a specific disease

Can determine if SNP is associated with disease by looking at people affected with disease and see if they have that particular SNPMicroarrays can help determine if SNP is relatedCreate DNA sequences that match DNA surrounding the SNP. One pair of DNA sequences matches one SNP and the other pair match the other SNPScientists get DNA from individual, highlight with fluorescent dye and see where the dye is on the microarray to determine the SNP presentSee if association exists (ie. People with SNP should have larger chance of contracting disease)Can determine if VNTR is associated by doing electrophoresis

Explain how continuous traits produce phenotypes

Continuous traits = Polygenic traits = Quantitative trait - traits influenced by multiple genes, often on different chromosomes (show graduation)Gene expression is complex, and continuous traits can also be influenced by environmental factors

Distinguish between dominant, recessive, autosomal, X-linked patterns of inheritance using pedigrees

Dominant: almost everyone will have itrecessive: two parents not having the trait give it to offspringx-linked: only in male, shows criss cross inheritanceautosomal: equal for male and female

principle of segregation

During meiosis, chromosome pairs separate into different gametes such that each of the two alleles for a given trait appears in a different gamete.

Distinguish between sister chromatids and homologous chromosomes

Each sister chromatid is a single double-stranded DNA and two sister chromatids join together by cohesions to form a chromosome (2 double stranded DNA). Two identical pieces of DNA (identical due to duplication during s synthesis phase of cell cycle)Homologous chromosomes have 4 sister chromatids (4 double stranded DNA). Chromosomes having same genes at same loci, but not necessarily, same alleles.

Explain and discuss how various factors might influence the relationship between genotype and phenotype

Factors that can influence the relationship between the two is the impact of the environment. Another can be recombination. There could be different phenotypes for the expected genotype leading to changes in the pedigree that was not anticipated.

ettings:Mode of inheritance - X-linked dominant Parental generation -Male - Mutant Female - Heterozygous Matings between relatives - disallow Progeny in first generation - 4S how carriers - turn off Why are all daughters, but only some sons, affected in the F1 generation?

Fathers pass on their X chromosome to their daughters, so all daughters in the F1 will have the disease.

Use pedigree analysis to calculate the likelihood an individual will have a particular genotype or phenotype

Find their genotype and then make a pedigree, probably have to use multiplication (occur simultaneously) rule or addition (either/or) rule

Define and relate the terms gene, allele, genotype, phenotype, homozygosity, and heterozygosity

Genes: DNA sequences that influence phenotypeAllele: The different forms of genes (eye color: blue, brown, green)Genotype:The genetic makeup of an individualPhenotype: The physical makeup of an individualHomozygous: It has the same genes and allelesHeterozygous: Different genes and alleles

Hemophilia is a sex-linked recessive trait in humans. If a carrier XX individual (heterozygous for the trait) mated with a non-affected XY individual, what would be the expected outcome(s)? Select all that apply.

Half the XY offspring would have hemophilia. None of the XX offspring would have hemophilia.

How did Mendel make crosses with his plants?

He grew plants from seeds and fertilized the ovules of one plant with the pollen from another.

A young man wants to determine if he is a descendant of Henry of Navarre and Eleanor of Aquitaine—two of his favorite historical characters. He sends a cheek swab to a DTC company and is offered a choice: the company can assess either the sequence of the man's Y chromosome or his mitochondrial DNA. Which should he choose?

He should get his mitochondrial haplotype sequenced, given the genetic variation in mitochondrial sequences compared to Y chromosomes.

In his cross, what did Mendel do?

He studied traits controlled by a single gene.

Interpret experiments to determine the relative influences of genes versus the environment on a given phenotype

If plants are put into different environment but remain the same, they are genetically influenced. If they are stated to be genetically identical but when put into different environments and change, they are affected by the environment.

Diagram the process of homologous recombination and explain how it can lead to new combinations of linked alleles

If you had linked genes ab/AB then recombinant strands are aB/AbThe farther they from each other, higher the recombination frequency, the more likely recombination will occur.

What are three ways in which meiosis I differs from mitosis?

In meiosis I, homologous chromosomes pair, cross over, and segregate from each other. In mitosis, sis chromatids separate and centromeres divide, which doesnt take place in meiosis I. 2 rounds cell division, gametes have only 1 set of allele (23 haploid chromosomes), unique gametes

Explain how incomplete dominance and epistasis affect the inheritance of a trait

Incomplete dominance takes the phenotype between the homozygous dominant and homozygous recessive. Epistasis is the interactions of genes (not the alleles) that suppresses each other. It is the interactions of genes that changes the phenotype of genotypes.Interaction between genes that modifies the phenotypic expression of genotypes.

•Describe Mendel's principle of independent assortment

Independent Assortment: Genes separate independently from each other. (metaphase I-anaphase I)

Settings:Mode of inheritance - Dominant Parental generation -Male - Heterozygous Female - Heterozygous Matings between relatives - disallow Progeny in first generation - 4 Show carriers - run simulation three times with "show carriers" on, and three times with "show carriers" off A carrier is an individual who has an allele associated with a trait but does not display the trait. They are, however, able to pass on the allele to their offspring. When setting the simulation's conditions as described, why does it make no difference whether or not you turn on "show carriers"

Individuals with one mutant allele express the disease phenotype and so cannot be carriers.

•Explain how independent assortment during meiosis can lead to new combinations of alleles of unlinked genes

It allows the homologous chromosomes to randomly be assorted and split so that the result can either be AdAd and aDaD or ADAD and adad.Happens during metaphase I

•Explain why the measured recombination frequency between any two genes is never greater than 50%

It can never be greater than 50% because only two of the sister chromatids cross over, meaning the other two sister chromatids don't participate in crossing over. So, at least half of the gametes will not have recombinant DNA for those particular genes

What effect does each successive mutation have on the colon cells in the example?

It causes them to divide more rapidly than normal cells.

Describe, using diagrams, the sequence of events involving DNA in meiosis from chromosome duplication through chromosome segregation

Meiosis I: homologous chromosomes separateEarly prophase I: Chromosomes become visible, pair of homologous chromosomes with sister chromatids visibleMiddle prophase I: crossing over occurs (recombination) of tetrads, sister chromatids from homologous pair come togetherLate prophase I: crossing over completeMetaphase I: tetrads line up in center of the cell at metaphase platerandom assortment of maternal and paternal sister chromatidsAnaphase I: centromeres do not split, only homologs separateMeiosis II: separation of sister chromatids*makes four unique gametes(PMAT) like mitosis, makes haploid cells with one copy of every gene

Explain how meiosis is different from mitosis

Meiosis has two separations that leads to 4 gametes (sex cells) with haploids. Meiosis has crossing over and independent assortment. Meiosis one, homologous chromosomes split and then meiosis two, the sister chromatids split (anaphases) First, meiotic cell division results in four daughter cells instead of two. Second, each of the four daughter cells contains half the number of chromosomes as the parent cell. (The word "meiosis" is from the Greek for "diminish" or "lessen.") Third, the four daughter cells are each genetically unique. In other words, they are genetically different from each other and from the parental cell.

Describe how nondisjunction can cause variation in chromosome number between gametes

Nondisjunction - when chromosomes don't separate properly In Meiosis 1:Homologous pairs stay together → two gametes with no chromosomes + two gametes with double the normal number of chromosomes In Meiosis 2:Sister chromatids don't separate → two normal gametes from other homologous chromosome + 1 gamete without chromosomes + 1 gamete with two sister chromatids of same chromosome

Explain how non-disjunction, recombination, and gene by environment interactions can complicate pedigree analysis

Nondisjunction and recombination can make pedigrees hard to follow because alleles are not passed on in the predicated mannerGenetic marker might be present, but normal phenotype is not because marker may have been separated from the traitGene by environment interactions - Unequal effects of the environment on different genotypes, resulting in different phenotypesEnvironmental conditions might make certain genotypes more or less likely to show a certain phenotypeNorm of Reaction - How environment affects phenotype across a range of environmental conditions, shows evidence of phenotypic plasticity for a genotype

The gene for nose shape is found on the X chromosome. Round nose is dominant to pointed nose. Human individuals with XXY (an additional X chromosome) are designated male. Individuals with XO (only one X chromosome) are designated female. Identify the possible nondisjunction events (rare mistakes during meiosis) that could explain the phenotype of the offspring produced by an XY parent with a pointed nose and a XX parent with a round nose have an offspring with Klinefelter Syndrome (genotype XXY) with a pointed nose. Select all that apply.

Nondisjunction could have occurred in meiosis 1 of the XY parent.Nondisjunction could have occurred in meiosis 2 of the XX parent.

Settings:Mode of inheritance - Recessive Parental generation -Male - Heterozygous Female - Heterozygous Matings between relatives - disallow Progeny in first generation - 4S how carriers - turn on Why is there a higher number of carriers than affected individuals?

Offspring have a 50% chance of being a carrier, but only a 25% chance of being affected.

For an individual who is heterozygous for two genes, Aa and Bb, what does independent assortment predict?

Offspring inheriting the dominant (A) allele of the first gene are equally likely to inherit either the dominant (B) or the recessive (b) allele of the second gene.

Refer to Simulation: Pedigree. Using the given settings, press "Generate Pedigree" three to six times, and notice the frequency of affected sons and daughters in the F1 to F4 progeny. Settings:Mode of inheritance - Y-linked Parental generation -Male - Mutant Female - Homozygous nonmutant Matings between relatives - disallow Progeny in first generation - 4 Show carriers - turn on Why aren't there any affected females in the F1 to F4 generations under these conditions?

Only males can be affected because the trait is linked to the Y chromosome.

telophase and cytokinesis

Pairs arrives at poles and cell is pinched apart, separating into two cells.

codominant alleles

Pairs of alleles that both affect the phenotype when present in a heterozygote; both equal expression

•Explain how genetic distance is different from physical distance on a chromosome

Physical distance - distance between genes on chromosomeGenetic distance - relative distance between genes in terms of map units (can be determined by recombination frequency)High recombination frequency → genes = far apartLow recombination frequency → genes = close together

Evaluate how genes and the environment can interact to influence a phenotype

Someone may have the genes for being tall, but if they come from an area where food is not in abundance and they are malnourished, they will not be tall.

metaphase I

The pairs of homologous chromosomes line up in the center of the cell. The centromere of each chromatid pair attaches to one spindle fibre.

When Mendel crossed yellow peas with green peas, the next generation was all yellow. How is this explained?

The parental plants pass one of their two alleles on to the offspring which is heterozygous, and the A allele is dominant to the a allele.

Describe Mendel's principle of segregation

The principle by which half the gametes receive one allele of a gene and half receive the other allele. (This is seen through heterozygous parents) (This is proved by test crossing proves this) (Mendel) (Metaphase I and Anaphase I)

At which phase(s) in your meiosis diagram does segregation of alleles take place? Explain your reasoning

The segregation of alleles takes place during anaphase 1 (metaphase 1 if specifically referring to the diagram). Anaphase 1 is where the homologous chromosome pairs separate, and so the mother allele and the father allele separate into different cells, resulting with half the gametes having the mother allele and the other half having the father allele. Anaphase 2 results in the splitting of sister chromatids, and so that makes sure that each gamete receives only one allele for each gene.

When a 9:3:3:1 ratio of phenotypes is produced by a cross between two individuals, which phenotypes are present in the rarest class that is represented by only 1 of the 16 possible genotypes of offspring?

These offspring have the recessive phenotype of both traits

Analyze VNTR DNA fingerprinting data to determine the genotypes and/or relatedness of individuals

They would get one allele/chromosome from dad and one from momcan be homozygous if each parent has that type of allelecan be heterozygous where one allele is from the dad and the other allele is from the mom

Imagine that a doctor sees a patient that is genotypically male, but is phenotypically female. How could this occur?

This patient likely carries a mutation in SRY that decreases SRY protein levels. The SRY gene codes for protein necessary for male development. A mutation in this gene can result in phenotypically female XY individuals.

robertsonian translocation

Translocation in which the long arms of two acrocentric chromosomes become joined to a common centromere, resulting in a chromosome with two long arms and usually another chromosome with two short arms.

Settings:Mode of inheritance - Recessive Parental generation -Male - Homozygous mutant Female - Homozygous nonmutant Matings between relatives - disallow Progeny in first generation - 4 Show carriers - turn off Why aren't there any affected individuals in the F1 generation?

Two recessive alleles are required to express the phenotype, and F1 individuals always receive one nonmutant allele from the unaffected parent.

What is the purpose of a testcross?

Usually used to determine whether a parent with a dominant phenotype is homozygous or heterozygous.

Explain the experimental processes of DNA fingerprinting using VNTR analysis

VNTR, variable number tandem repeat, is the spot on genome where DNA sequences repeat and this length and repetition differs among genomes. The PCR is used, with it's primer duplicate (amplified) the specific repeated sequence. It is then ran in the gel electrophoresis to see the bands and find if there are matching ones (DNA fingerprinting).

Describe how variation can be measured, and what can be done to distinguish genetic and environmental sources of variation

Variation can be measured by the difference between a parents phenotype and the offspring's phenotypeBy plotting the mean of parents' trait against the mean of the offspring's trait, we can determine how much the trait is affected by genes or by the environment.If it were only affected by genes then the slope would be 1If it were only affected by the environment then the slope would be 0 (offspring phenotype is determined by the population mean)

Define the terms X-linked gene and Y-linked gene

X-linked genes are genes that are on the X-chromosomes. If the gene is on the mother, it will be passed to the son and the son will eventually pass it on to the daughter.Y-linked genes are genes on the Y-chromosomes this means that only the male in the family will receive the gene.

types of nondisjunction that can happen

XXY, XYY, XXX, XO

A researcher is creating pedigrees for a trait he suspects to be dominant in humans. What are some of the likely features of his pedigrees for families with this trait? A) None of the other answer options is correct. B) Only females will have this dominant trait. C) The occurrence of mating between individuals with this trait will be high, as all dominant traits are common within any given population. D) All the offspring of a mating where one parent has the trait will themselves be affected. Score: 1 of 1

a

After doing PCR on the same region between two individuals, you notice that each person's DNA yielded pieces of different sizes. Which of the following is the MOST likely explanation? A) This is an example of VNTRs. B) A mistake was made during the PCR. C) A mistake was made during gel electrophoresis. D) This is an example of RFLPs. E) None of the answer options is correct.

a

Which of the choices is a characteristic of meiotic cell division? A) Cell division results in the production of gametes. B) Meiotic cell division ultimately results in the formation of two cells. C) Meiotic cell division requires two rounds of DNA replication. D) The cells produced by meiosis are genetically identical.

a

hich of the examples would be good examples of genotype-by-environment interactions? Select all that apply. A) a strain of corn whose yield varies with the amount of nutrients in the soil B) a line of dairy cows that increases milk yield in relation to feed amount C) two different strains of corn that differ in height due to genotype D) a line of chickens whose eggshells are extra thick regardless of feed type E) two different mutants of mice that share similar fat metabolism abilities F) a strain of mutant mice that becomes obese regardless of feed amount

a b

in norm of reaction plot: The actual offspring mean height in the graph lies between the parental mean line and the population mean because: (Select all that apply.) A) the phenotypes of the parents result from both their genes and their environment. B) uring meiotic cell division segregation and recombination break up combinations of genes leading to extreme phenotypes (e.g., very tall or very short). C)the phenotypes of the offspring result from both their genes and their environment. Score: 1 of 1

a b c

environmental risk factor

a characteristic in a person's surroundings that increases the likelihood of developing a particular disease

What is a single-nucleotide polymorphism (SNP)?

a difference between two sequences at a single nucleotide position in a DNA sequence

The Y-linked trait of hairy ears has been passed down for many generations in a certain family. A hairy-eared male in this family would be expected to have:

a paternal grandfather with hairy ears.

why are common diseases considered complex traist

affected by both genes and environemnt

whats complex trait

affected by both genetic and environmental factors to contribute to phenotype variation

What are some reasons why a single trait might not show a 3 : 1 ratio of phenotypes in the F2 generation of a cross between true-breeding strains, and why a pair of traits might not show a 9 : 3 : 3 : 1 ratio of phenotypes in the F2 generation of a cross between true-breeding strains?

affected by more than 1 gene, or affected by the environment. or is incomplete dominance, or incomplete penetrance or variable expressivity, or some phenotypes show more than others. same w pairs of treats.

If an XY male carries a mutation on his X chromosome, _______________ will receive the mutant X.

all daughetsr

what does slope of 0 in heritability mean?

all environment; offpsirng mean=pop mean

what does a slope of 1 in heritability mean?

all genetic, so offspring mean=parental mean, and 100% heritability

The principle of independent assortment states that:

alleles of a gene pair assort independently of other gene pairs.

When do sister chromatids separate in meiosis?

anaphase II

Genes located along the X chromosome:

are called X-linked genes.

Genes in different chromosomes _____ during meiosis. Genes that are very close together in the same chromosome are _____.

assort independently, linked

Most complex traits are:Select all that apply. A) inherited in pedigrees showing simple Mendelian patterns. B) affected by multiple genes. C) homozygous for all alleles affecting the trait D) .heterozygous for all alleles affecting the trait E) .affected by environmental factors F) .affected by interactions between genes and environmental factors.

b e f

If you crossed two heterozygous yellow-seed pea plants (genotypes Aa), the relative frequency of: A) homozygous yellow-seed plants (genotype AA) would be 1/4. B) All of these choices are correct. . C) the A allele in each parent's gametes would be 1/2. D) green-seed plants (genotype aa) would be 1/4. E) the a allele in each parent's gametes would be 1/2.

b: This would resemble the F2 generation of a mating between two true-breeding strains

. You are now trying to map a new gene locus (Gene X) on chromosome 9. You have determined that the recombination frequency between Gene X and Gene A is 12.5%, recombination frequency between Gene X and Gene B is 25%, and the recombination frequency between Gene X and Gene C is 31.25%. Use this information to determine the location of Gene X.

bc adding

why is heritability important

bc can determine how rapidly a pop can be changed due to artificial selection

How is it possible that there are multiple different alleles in a population, yet any individual can have only two alleles?

bc in pop there are many chromosomes copies, so can have multiple allele present in diff chromosome.

how do genetic markers work

before/after a particular disease that can b associated w/ nearby disease

A mutation arises in a bacterium that confers antibiotic resistance. Is this mutation harmful, beneficial, or neutral?

beneficial to bacteria when antibiotic is present, but can b neutral or harmful in absence of it. depends on evnvironment

With regard to mutations, what is meant by the terms "harmful," "beneficial," and "neutral"? Why it is sometimes an oversimplification to consider a mutation as harmful, beneficial, or neutral?

beneficial=advantage. neutral= no affect on reproductive or survival capacity. It rlly dependson situation and environment

What are some of the benefits and risks of genetic testing and personal genomics?

benefits is find disease. but discrimination due to health and genetics

A researcher discovers a new type of plant. After setting up several crosses, she assesses the mitochondrial sequences in the F1 generations and compares these to the mitochondrial sequences in the parental generation. In the progeny, she finds sequences that are similar to both the maternal and paternal sequences in the parental generation. These plants demonstrate _____ inheritance of their organelles.

biparental In plants, mitochondria can be inherited from either parent.

signs of mitochondrial disease in linkage

both male and female. affect female transmit trait to all offspring, male don't transmit trait. affects energy and muscle

Which is true? A) Down syndrome is caused by errors in fertilization. B) Down syndrome is the one inherited disorder that results from an extra copy of an entire chromosome. C) Errors in chromosome segregation can occur in either the first or second meiotic division. D)Nondisjunction can only produce gametes with extra chromosomes, not missing chromosomes.

c

Which of the statements is true of incomplete penetrance? A) Incomplete penetrance implies that some individuals will experience less severe forms of disease such as cancer or Alzheimer's. B) Incomplete penetrance refers to cases in which individuals developing a particular disease (e.g., cancer or Alzheimer's) lack the typical genotype for this disease. C) For genes with incomplete penetrance some individuals can show the trait while others with the same genotype may not. D) Environmental factors do not influence penetrance.

c

Which statement is not an example of a complex trait? A) grain yield in corn B) height in humans C) smooth or wrinkled pea seeds D)milk production in dairy cows

c

The data shown are the results of growing one strain of a crop plant in soils with different nitrogen concentrations.If a different strain of the same crop plant were grown in the same soil conditions, you would predict that: A) it could respond the same way or differently because the environment has too many variables to predict. B) it would respond the same way to soil nitrogen concentrations because they are the same type of crop plant. C) it could respond the same way or differently; different genotypes can, but may not always, respond differently to soil nitrogen concentrations. D) it would respond completely differently to soil nitrogen concentrations because they are different strains.

c, This question is asking for a prediction of the norm of reaction for a related crop plant. One of the things that can make different strains of the same crop plant show different responses are the genotype-by-environment interactions. Although the strains would be different genetically, how those strains differ may have no effect on the response to soil nitrogen concentrations. By the same reasoning, the genetic differences may show a different norm of reaction to soil nitrogen concentrations compared to the data presented in the question.

how to indentify coding sequences?

can look for hybridization b/w cloned DNA and human cDNA library, & DNA from other species, or seq clones and look for telltale signs of coding seq

A heterozygous female harboring one mutant allele for hemophilia is called a(n) _____ for that trait.

carrier

describe prophase of meiosis

chromosomes condense, meiotic spindle form, chiasma (bivalent) form with crossing over

Why don't linked genes exhibit independent assortment?

close enough crossing over unlikely to occur

How can recombination frequency be used to build a genetic map

closer together=smaller recombination frequency

describe crossing over

crossing over is when homologous chromosomes exchange genetic information this helps provide genetic variety; only between inner two sis chromatids

In crosses involving linked genes, recombinant offspring result from:

crossover

Which of the answer choices is true of a cross involving a sex-linked gene (one on the X or Y chromosome) but not of a cross involving an autosomal gene? A) A Punnett square cannot be utilized for illustrating the possible outcomes of a cross involving a sex-linked gene. B) Only autosomal genes observe the law of segregation. C) Recombination, or crossing over, cannot take place between the X and Y chromosomes. D) The phenotype outcomes of XX offspring and XY offspring can be different E) .Both parents have two copies of a sex-linked gene.

d

Which of the statements best reflects the extent to which we can distinguish the effects of genes and the environment on the expression of a complex trait? A) About 80% of an individual's height is determined by genes and 20% by environment. B) For identical twins raised in the same environment, height should not differ by more than 20%. C) If one individual is 60 inches tall and another is 70 inches tall, they differ in about 80% of their genes. D) In a group of individuals of the same sex, about 80% of the variation in height among individuals is due to genetic differences and 20% is due to environmental differences.

d

Which of the statements concerning cancer and mutations is correct? A) Usually a single mutation is all that is required to cause cancer. B) None of the other answer options is correct. C) Cancer can only occur with a mutation in a somatic cell. D) Usually multiple mutations are required in different genes to cause cancer. E) Cancer can only occur with a mutation in a germ cell.

d

Which of the choices is an accurate statement that accounts for why women with the genotype XXX are not phenotypically different from an XX female? A) The extra X chromosome only becomes active in nonreproductive areas of the body. B) Cells normally have enzymes that recognize and degrade extra X chromosomes. C) The X chromosome only carries genes dealing with being a female, so having another one doesn't matter. D) Only one X chromosome is active in each cell, regardless of how many X chromosomes there are in a cell. E) None of the answer options is correct.

d X-chromosome inactivation in female cells shuts down gene expression of all X chromosome copies but one, no matter how many copies of the X chromosomes there are.

how can heritiability change

depending on pop and ocndition

Mammals are _____ and produce _____ gametes.

diploid and haploid

what must happen before meiosis

dna replicated

Huntington's disease is a devastating neurological disorder. If a child of an affected parent receives one copy of the Huntington allele, he or she will develop Huntington's disease. Thus, Huntington's disease is considered a _____ trait

dominant

You are examining a human pedigree for a trait. You notice that the trait appears in every generation, is equally likely to occur in males and females, and about half of the offspring are affected when one parent is affected. The trait is most likely:

dominant

how do gene hunters look for genetic markers

dont know where gene is, clone entire region w/ overlapping clones to put each clone in proper order

how do translocation relate to cancer

double strand breaks cause arrest in mitsosi or apoptosis, so activate cell DNA repair, which cna produce oncogenes. can make coding sequences close to protooncogene leading to more promoters and overexpression, or fuse coding sequences together, or alter gene expression by put a new promoter near coding region.

environmental variation

due to diff in environment

genetically identical strains of corn differ in height

due to environment

Review the pedigree shown and choose the most accurate statement about the inheritance of an X-linked recessive mutation. A) The offspring of an affected male are usually affected. B) The sons of the sisters of affected males will always be affected C) .Daughters of affected males are always affected. D) The brothers of affected males are always affected E) .For recessive X-linked traits, most of the affected individuals are males.

e, For X-linked traits, males only need one copy to express the trait in their phenotype. Females would need two copies of the recessive allele to express the trait in their phenotype.

what does genotype by environment interaction imply

effect of genotype can't be specificed w/o knowing envirnoment and vice versa

What is the biological basis for the 1 : 1 ratio of males and females at conception in mammals?

egg cell only have x, sperm have y and x

all same strain corn plants grown in same environment w/ variation

environment influence

what if norm of reaction line is flat

environment no efefct

What are some factors that influence variation in complex traits

environmental factors and genetic factors

what graphs for norm of reaction?

environmnet change x axis, phenotype resulton y axis

When one gene is able to modify the effect of a second gene, the phenomenon is known as:

epistasis

signs of dominance inheritance

equal girl and boy, most only 1 affect parent, among 1 affected parent 1/2 offspring affect s

t or f: A phenotype always refers to something that you can see with your eyes, like hair color or eye color. falsetrue

f

t or f: All organisms have either an X or Y chromosome, as these chromosomes are solely responsible for determining the sex of an individual.

f

t or f: An example of regression toward the mean occurs if the offspring of two short parents had an average height equal to the average height of the parents, not of the population as a whole.

f

t or f: During meiosis in female mammals, sex chromosomes segregate to produce two types of eggs: X-bearing eggs and Y-bearing eggs.

f

t or f: Harmful mutations are always quickly weeded out of a population.

f

t or f: Physical exchange between homologous chromosomes (crossover) occurs during metaphase I of meiosis.

f

t or f: The observable characteristics of an organism constitute its genotype.

f

t or f: True-breeding plants are typically heterozygous for most genes.

f

t or f: An individual is heterozygous for two linked genes, but whether its genotype is AB/ab or Ab/aB is not known. The individual is crossed with an ab/ab individual, and among the progeny are: 16 AB/ab; 54 Ab/ab; 46 aB/ab; 24 ab/ab.These results imply that the genotype of the doubly heterozygous parent was AB/ab.

f, false The recombinant (non-parental) chromosomes occur in smaller frequencies than the non-recombinant (parental) chromosomes in matings where two genes are linked on the same chromosome.

What is nondisjunction?

failure of chromosomal separation

t or f: First-division nondisjunction will only yield gametes with an extra chromosome, whereas second-division nondisjunction will only yield gametes missing a chromosome.

false First-division nondisjunction results from failure of homologous chromosomes to separate during meiosis I, and all gametes formed after first-division nondisjunction have either an extra copy or a missing copy of the homolog. Second-division nondisjunction is failure of sister chromatids to separate in one of the two daughter cells undergoing meiosis II. The two gametes formed from that division will have either two copies or no copies of that chromatid. The other two gametes formed from the unaffected cell will be normal.

t or f: Similar to single gene traits, traits determined by multiple genes also show the expected 3:1 ratio of phenotypes in the progeny between two heterozygotes

false Three different genes that segregate independently results in an 8x8 Punnett square with a total of five different phenotypes that are normally distributed among the offspring

The _____________ two loci are on a chromosome, the more likely they will be separated by crossover events during gamete formation, and thus the frequency of recombination between loci on a chromosome can be used to measure the _______________ between those loci.

father apart, genetic distance

How might you go about determining the relative importance of genes and the environment for variation in risk for a complex trait such as type 2 diabetes?

feed 2 strains normal, high fat diet, low fat diet and see how they change

how do u reestablish diploid number?

fertilization

how to do dihybrid crosses

find out all of the possible gametes for each genotype thing, like AaBb have four possible gametes. then, punnett square alllll the possible gametes of each one: AB Ab aB ab x AB Ab aB ab

F1

first generation offspring

In normal meiosis, when do homologous chromosomes separate from each other?

first meiotic division

How do most cancers arise?

from a series of mutations that arise in the descendants of a single somatic cell

if a mutant gene allows more calcium to enter cell, what does the mutation do?

gain of function

if AB show up together often, what does that mean?

gene AB are linked

What are the differences among gene, allele, genotype, and phenotype

gene is unit of heredity. allele is diff form of gene. genotype is combo of allele in individula. phenotype is trait expression

The number of new mutations in genomes following a round of genome replication:

generally increases with larger genomes. Although the rate of mutation per nucleotide might be similar in different organisms, the bigger the organisms' genome, the higher the total number of mistakes that are left unrepaired.

Why can the effect of a genotype on a phenotype not always be determined without knowing what the environment is? Why can the effect of a particular environment on a phenotype not always be determined without knowing what the genotype is?

genes and environment interact in unpredictable ways; genotype by environment interaction

what are linked genes

genes located on the same chromosome that tend to be inherited together

In genetic crosses, the symbol Aa refers to a:

genotype

how does genotype of individual relate to phenotype?

genotype affects phenotype

What determines a genotype? What determines a phenotype?

genotype has 2 copies of allele, can be homo or heterozygous. phenotype is influenced by genotype and environment

Mutations in which types of cell are most likely to contribute to evolutionary change in a population of organisms? Why?

germ line, bc those are transferred to progeny

Compare and contrast the inheritance of germline and somatic mutations

germline passed onto offspring, somatic stay within individual and not all cell

what did mendel observe that leads him to principle of segregation

half gametes have 1 allele, other half have other one

what are gametes? haploid or diploid?

haploid; only 1 set of chromosomes, not 2.

An organism that has two different alleles of a given gene has a(n) _____ genotype.

heterozygous

how does heritability reflect aritificial selection

high heritability responds rapidly to it, low responds slowly

Prophase of meiosis I has some important differences from prophase of mitosis. These differences include: ___________ pair, and _________ occurs in meiosis.

homologous chromosome, crossing over

A testcross involves crossing with a(n) _____ individual and is used to determine the _____ of the tested parent.

homozygous recessive, genotype

What does true-breeding mean?

homozygous' expression of each trait in original strains

Sites in the genome that are more susceptible to mutations than others are called:

hotspots

norm of reaction

how environment affects phenotype across a range of environmental conditions

examples of epistasis

if dominant I gene, inhibits C gene so no pigment.

how not to identify coding sequences?

if use DNA instead of cDNA, hybridization will reveal noncoding seq too instead of j coding seq

describe synapsis

in meiosis prophase, homologs in bivalents exchange information

familial muation

in sex cells so IS passed on to offspring

polygenic traits are

influence by multiple genes

what happens when multiple genes affect same phenotype and epistasis?

inhibitor present, blocks expression of pigment, like in the lab dog coats.

describe how to use rflp

it cuts the band at places. These causes breaks in the segments; if homozygous with break=two alleles. If no break, then 1 band.

For a recessive X-linked mutation, such as color blindness, what is the pattern of inheritance from an affected male through his daughters into her children?

mate w/ homozygous nonmutant female, all sons normal all daughters heterozygous. daughter mate w normal male, half sons affected, and half daughter are heterozygous and nonmutant homozygous

how is mitochondria dna usually passed

maternal bc of cytoplasm in mammals

mitochnodrial dna

maternally bc mom has cytoplasm in eggs. separate genome and more genetic diversity, mom pass on to all offspring, males dont pass on. better bc more precise and tracked finer scale and more info than y linked

What is the difference between the mutation rate for a given nucleotide and the mutation rate for a given cell?

mutation rate for given cell is higher; more dna replication in cell means more chance for mutations. bigger cell genome, that means more chance for mutation

genetic risk factor

mutations that increase risk of getting a disease

Consider a gene with n alleles A1, A2, ..., An. How many distinct heterozygous genotypes are possible?

n(n- 1)/2 The combinations that are different are the product of the number alleles times the number of alleles less one, since it cannot include the first allele with itself. Divide by two to account for reciprocal, but genotypically identical, pairs.

what are the two types of translocation

non reciprocal is 1 way, translocation transfer to nonhomologous chromosome. Reciprocal is 2 exchange nonhomologous chromsomes. i

look at the bruin problem

okie

An allele is:

one of several forms of a gene.

Why is the upper limit of recombination 50% rather than 100%?

only 2 of four chromatids are recombinant

What is the pattern of inheritance expected from a Y-linked gene in a human pedigree?

only males affected, sons all have it, no female

P1

parental generation

graph for heritibaility?

parental genotype on x axis, offspring genotype on y axis

describe dna fingerprint/vntr

pcr amplify by primer attach and add polymerase to extend dna out. smaller travel further, so less repeat travel further. homozygous band, heterozygous 2 band. vntr is flanked by uinque sequence that primer attach to

Why are some complex traits also called quantitative traits?

phenotype measured on a scale w/ small intervals, canbe determined by coutning or measureing

what does it mean when mutation is rare

ppl outside of it will not have it; homozygous dominant, wont be carrier either. Parents most likely wont have it if unkonwn, only carrier.

While doing a pedigree analysis of a European royal family, you notice a disease in a female child of two healthy parents. There are also some cousins with the same genetic disease. If this disease is controlled by a single gene, then the most likely explanation for these observations is the disease is:

recessive and only seen in homozygous recessive individuals such as the daughter.

Construct a human pedigree for a dominant trait and a recessive trait. What are the patterns of inheritance in each?

recessive not occur in every gen and nonaffected have affected children. dominant affect every gen and also half of children affected

relationship b/w frequency and map unit

recombination freq is meausre of genetic distance, 1% is 1 map unit

what 2 components of hypothesis

relationship b/w ind and dep variable, prediciton based on that releationship

describe translocation carriers

reproductive issue. aneuploid is excess of some genes and deficient in other. euploid is both translocation product in gamete or 2 normal chromsome (alt segregation). `

Mutations that destroy or create a cleavage site for a restriction enzyme are the source of:

restriction fragment length polymorphisms

Nondisjunction results in gametes that violate which principle?

segregation Nondisjunction violates Mendel's principle of segregation because homologous chromosomes fail to separate in meiosis and gametes can contain both alleles or no allele of a gene.

How does segregation relate to meiosis

segregation of alleles reflect separation of chromosomes in meiosis. gene pairs carried on homologous chromosomes, so segregate in anaphase I.

How do the mechanics of meiosis and the movement of homologous chromosomes underlie Mendel's principles of segregation and independent assortment?

segregation reflects chromosome separation in meiosis I, independent assortment reflects when chromsomes assort into daughter cells randomly

hierarchy of dominance

some traits have hierarchy of dominance

t or f: In humans, fruit flies, and many other organisms, most of the genes on the X chromosome are not found on the Y chromosome

t

t or f: The genotype of a fetus can be screened for SNPs associated with some diseases.

t

t or f A trait with high heritability responds strongly to selection, whereas a trait with low heritability responds slowly or not at all.

t, The response of a trait to selection depends on two factors: the heritability of the trait and the strength of selection. If heritability is high, the trait will respond to selection. If heritability is low, the trait will not change very much in the next generation, even if strong selection is applied.

t or f: Genotype-by-environment interaction means that genetic and environmental influences may interact or contribute to the phenotypic outcomes in unpredictable ways.

t; Norms of reaction show how phenotype can change depending on environmental conditions

Single-nucleotide polymorphisms (SNPs) can be detected by microarrays, which are wafer-like substrates to which millions of short stretches of DNA are attached. A microarray consists of many different squares, each one containing a different sequence of single-stranded DNA to which fluorescently labeled strands of DNAs from patients with different SNPs can hybridize. If one square will hybridize with an SNP having a C-G base pair at a particular site, and an adjacent square will hybridize with an SNP having a T-A base pair at the same site, which of the genotypes will hybridize with both squares and make them fluoresce?

the heterozygous C-G/T-A genotype One allele (C-G) of a heterozygous individual would hybridize with the first square, the other allele (T-A) with the second. Both homozygous genotypes would hybridize with only one square.

null hypothesis

the hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error. Logical opposite of hypthoesis

what is the frequency of recombination

the proportion of recombinant chromosomes among the total number of chromosomes observed

How do u distinguish whether yellow seeds in mendel were AA or Aa

the seeds produced when self fertilize. Or test cross

artifical selection

the selective breeding of organisms by humans for specific characteristics

describe how to use vntp

the shorter it is, the longer it travels. Parents must have that allele to pass onto children. homozygous is 1 band, heterozygous is 2 bands. use pcr

Why does it not make sense to try to separate the effects of genes ("nature") and the environment ("nurture") in a single individual, whereas it does make sense to separate genetic and environmental effects on differences among individuals?

they're so intimately related. possible to separate population based on their affecting variation

How can the human X and Y chromosomes pair during meiosis even though they are of different lengths and most of their genes are different?

through regions of homology in meiosis on chromosome arms

y linked genes no exhibit independent assortment

too close together=unlikely cross over happen between it

Which of the traits depicted in the graph shown has the lowest heritability?

trait L A slope of zero shows low heritability and variation that is due almost entirely to environmental effects. Any deviation from a slope of zero reflects a trait with some amount of heritable genetic variation.

signs of recessive inheritance

trait can skip 1+ gen, affect ppl equally, affected may have nonaffected parents, affected individual often result from mating b/w relative

y can u use punnett squares for dihybrid crosses?

u can use 2 diff ones bc of independent assortment

how does female cytoplasm divide

unevenly; most in oocyte, smaller ones that dont go are polar podies

In his famous paper, Mendel writes that he set out to "determine the number of different forms in which hybrid progeny appear" and to "ascertain their numerical interrelationships." How did his approach differ from earlier investigations in heredity?

used pure breeding strains, studied 1 or few traits at a time, and counted progeny of crosses

rflp?

variation of length produced by restriction enzyme

what does test cross mean

when cross by homozygous recessive, if AA then would all be Aa heterozygous. if Aa, then half is aa.

x linked gene, how passed on?

x linked on x chromosome. expressed in males. Males give it to their daughters, get from mom. criss cross inheritance

y linked gene

y chromsome, only share a little bit w X, passed down through males, separate lineage so mutation accumulate

How can Y-chromosome data can be used to trace ancestry

y linked genes have complete linkage , no crossover, separate lineage can be traced

What are the genotypes and phenotypes for Mendel's true-breeding parent plants?

yellow AA, green aa

Visualize how meiosis produces four haploid gametes

yes bc yes

s it possible for an unaffected female to have female offspring with red-green color blindness?

yes if shes heterozygous and meets w someones whos color blind

is it possible not to lose genetic info intranslocation

yes, balanced translocation.

Is it possible for two individuals to have the same phenotype but different genotypes? The same genotype, but different phenotypes? How?

yes. AA and Aa have diff phenotype. traits influenced by environment and others have diff pehnotypes

Predict how chromosome numbers in a gamete may vary depending on non-disjunction during meiosis

yres