BIOL 3000 Genetics - Auburn Dr. S - Exam 2

Pleiotropy

one gene, multiple traits, multiple alleles

Epistasis

multiple genes, one trait, one loci; TWO (2) or more different gene products acting together to modify a phenotype.

Upstream

has to be turned on before a particular gene to achieve a phenotype

Downstream

has to be turned on after a gene to achieve a phenotype

Loci

Epistasis occurs whenever two or more ____ interact to form a new PHENOTYPE.

Recessive Epistasis

HOMOZYGOUS RECESSIVE genotype determines phenotype

16

Total of phenotypic ratio from recessive epistasis dihybrid heterozygote cross?

True

Genotype BBee is true breeding.

Double Recessive Epistasis

Either HOMOZYGOUS RECESSIVE genotypes results in the same phenotype

duplicate recessive

Another name for double recessive epistasis?

Dominant Epistasis

One ALLELE for a DOMINANT trait hides the phenotype of the other GENE

Double Dominant Epistasis

Both GENES are DOMINANT and the protein products result in the SAME trait

Dominant Recessive Epistasis

Sometimes, a DOMINANT allele in one locus and RECESSIVE alleles in another locus can produce the same phenotype

All

Which cells are sex chromosomes located in?

ALLOSOMES

(sex chromosomes) a chromosome that differs from an ordinary autosome in form, size and behavior. Determines the sex of an individual organism.

AUTOSOMES

(non‐sex chromosomes) appear in pairs whose members are homologous but differ from other pairs of

Hemizygous

What is XY (Heterogametic) called?

XX or XXY

Fruit Fly female

XO or XY

Fruit fly male

ZW

Female bird

ZZ

Male bird

Aneuploidies

abnormal number of chromosomes

SRY Gene

Sex-determination region (can move around)

Week 6/7

When is sex determined in development?

Male

SRY+

Female

SRY-

PAR

Pseudoautosomal Regions

Differential Regions

contain specific genes that have no counterparts on the other Sex Chromosome

No

if the F1 and F2 have the same ratio for a reciprocal cross is it sex linked?

LINKAGE

The PHYSICAL CONNECTION that exists between genes when their loci are on the same chromosome.

SEX LINKED TRAITS

Traits whose loci are located on the SEX CHROMOSOMES so that their transmission from one generation to the next is affected by which SEX CHROMOSOMES an individual acquires

More

X‐Linked Recessive Traits appear much ____ commonly in males than in females.

Mother

Males will ALWAYS receive their X Chromosome from their _____ and will always express ANY X‐Linked traits their _____ has

Color blindness

example of x-linked trait

Retinitis pigmentosa

example of y-linked trait

Holandric traits

traits passed directly from FATHER to SON on the Y Chromosome

Sex limited traits

Generally AUTOSOMAL; expressed in ONLY ONE GENDER

Sex influenced traits

Autosomal but is expressed differently by 2 genders

Chromosome Theory of Inheritance

correctly explains the underlying mechanism of Mendelian genetics by combining chromosomes with the paired factor postulated by Mendel

Genetic Linkage

Two genes are closely associated on the same chromosome

Linkage

when two (or more) GENES are inherited together

Linkage

The loci of the genes have to be on the same chromosome for what mode of inheritance?

No

Does linkage independently sort?

100:100:100:100

Independent assortment ratio

200:0:0:200

Complete linkage ratio

175:25:25:175

Incomplete linkage ratio

No. prevent breaking gene

Does crossover occur in complete linkage? Why?

Complete linkage

Which only has parental or recombinant?

Configuration

Arrangement of alleles on homologous chromosomes

Cis‐configuration

Normal (WT) alleles on one chromosome, mutant alleles on the other

Trans‐configuration

Each chromosome contains one normal (WT) allele and one mutant

Complete Linkage

LOCI are VERY close together on the chromosome and CROSSOVER does not occur

Recombination

Exchange of UNIQUE GENETIC MATERIAL between NONSISTER CHROMATIDS during Meiosis.

Crossing over

exchange of genetic information between non‐sister chromatids

Incomplete Linkage

RECOMBINATION occurs between TWO LOCI. The amount of (or frequency) of RECOMBINATION depends on how far apart the two LOCI are

GENETIC MAPPING

Methods used to identify the distance between genes

Chiasmata

the point of contact, the physical link, between two chromatids belonging to homologous chromosomes

Cis Incomplete linkage

Which results in more parentals than recombinants?

Trans Incomplete linkage

Which results in more recombinants than parentals?

Incomplete linkage

If you have recombinants you have ______?

Genetic mapping

Methods used to identify the distance between genes

measurable, fixed

If a gene's loci had a specific place on a chromosome, then the distance between any two genes was a ______ number

Centimorgans, mapping units

measurement of genetic mapping

Independent assortment

if a recombinant frequency is 50% or more then it is ______ ?

Closer, lower

The _____ the loci of the genes are on a chromosome the _____ the recombination frequency

Single gene crossover

one gene going from one chromosome to another

Aren't

If the recombinant still look like the parentals (in reference to specific genes) then they ______ actually recombinants-they are parentals.

Different

When doing three point mapping, the recombinants are referred to the one gene that is _____ from the parentals

Cytology

study of cells

Karyotype

Chromosomes arranged by size; Largest is chromosome 1, second largest is no. 2, etc.

Spectral karyotyping (SKY)

uses single stranded fluorecently labeled DNA probes to unique regions of chromosomes

Euploidy

changes in WHOLE chromosome sets

Aneuploidy

changes in parts of chromosome sets

Haploid (n)

half the number of chromosome sets

Diploid (2n)

two copies of each chromosome set

Triploid (3n)

three copies of each chromosome set

Aberrant euploidy

changes in the number of chromosome sets

polyploidy

more than two chromosome sets

Tetraploid (4n)

four copies of each chromosome set

Monoploid

organism has the haploid # of chromosome but isn't haploid (n)--rather 1n; characteristically sterile

Parthenogenesis

asexual reproduction where an embryo develops from an unfertilized egg

Automixis

Meiosis proceeds normally; The meiotic products fuse, restoring diploidy; The offspring are half clones of the mother

Apomixis

goes through meiosis from one gamete; gametes are produced kind of like mitosis; clones

Size

correlation between numbers of chromosome sets and ____ of the organism

Colchicine

chemical microtubule inhibitor (inhibits anaphase)

Autopolyploids

Having more than one set of chromosomes originating within a species

Allopolyploids

Hybrids of two different species with more than one chromosome set

Errors in mitosis

How does autopolyploids occur?

Autopolyploid Triploids

How does seedless fruits occur?

Allopolyploids

What occurs when two different species crossbreed and then experience a chromosome doubling event?

Embryoids

pluripotent stem cells (haploid content)

Allopolyploid organism

Triticale (cross between wheat and rye)

Can differ

Chromosome numbers _____ either by greater or smaller than the normal individual

2n‐1

Monosomic

2n+1

Trisomic

XXY, XYY, XXX or XO

Sex Chromosomes

Full form

all cells in the organism display the Aneuploidy, either gain or loss of a chromosome (mechanism that caused this to form happened early in development)

Partial form

all cells in the organism display the Aneuploidy however, you do not have complete gain or loss of a chromosome, only a part of the chromosome is changed (addition or loss of a p or q arm)

Mosaic form

not all cells display the Aneuploidy (happens when a defect happens later in development-ex. Mesoderm develops the aneuploidy)

Nondisjunction

abnormal segregation of homologous chromosomes (leads to aneuploidy)