genetics exam 2 (SI notes) Flashcards

Incomplete and codominance

occurs when there is not a distinct dominant allele shown in the heterozygote. ex: a mix of a red and white flower making it pink

occurs when BOTH the dominant and recessive alleles are detectable in the heterozygous organism. ex: a brown and white cow makes a brown cow with white spots

A gene is so mutated, that if an organism has two mutated copies, it will not survive to term

lethal alleles are naturally selected out of the population, as there is no
viable phenotype

lethal alleles still exist at low levels. This is because heterozygotes still carry the lethal alleles

They can kill an offspring before it reaches term, or they can have a delayed age of onset

means that with only one Wild type allele, you produce the normal
phenotype (typically dominant)

means that only one Wild type allele can NOT produce the normal
phenotype (typically dominant)

It is the COMPLETE loss of gene function as compared to wild type. ex: a pigment that was brown know no longer produces color.

A partial loss of gene function

When one mutation inactivates several parts of a protein complex

hypermorphic and neomorphic mutations

It occurs when a gene becomes more active than normal and it continues normal gene activity, but at a higher rate

It occurs when a gene takes on a NOVEL, or completely new function.

They on autosomes, but due to hormonal differences, are only expressed in one sex.

They occur on autosomes, are expressed in BOTH sexes, but have
different inheritance patterns due to hormonal differences. ex; baldness in males

true

It is the degree to which a genotype correlates with a phenotype

The genotype always corresponds with the phenotype

They do not match genotypes and expected phenotypes. ex: when R is round and r is wrinkled, a rr plant is round

Traits that sometimes match genotypes and phenotypes and sometimes don’t

The same genotype can present in varying degrees. Ex: the NF1 traits with bumps

Environmental and epigenetic factors

When the environment plays a role in regulating gene expression, which may contribute to this variable expressivity and incomplete penetrance

where one genotype causes multiple different phenotypes at once. ex: sickle cell causing different symptoms

occurs when multiple genotypes combine to code for one phenotype. ex: height being controlled by multiple gene interactions

when one gene alters the expression of another gene

Its when two genes together contribute to a given phenotype...(9:7 ratio)

Occurs when two genes are redundant of one another and only one genotype is required to produce the same phenotype... (15:1 ratio)

occurs when a phenotype is present only when BOTH dominant alleles
are present, if only one is present there is a third phenotype... (9:6:1 ratio)

when a homozygous recessive genotype in one gene masks the expression of the second gene, regardless of what it is...(9:3:4)

when a dominant genotype in one gene masks the expression of the second gene, regardless of what it is...(12:3:1)

when one dominant allele suppresses another dominant allele...(13:3)

It occurs when two genes are so close together, that their alleles segregate together instead of independently. It isa direct contradiction to Mendel’s law of independent assortment

Genes on the same chromosome

true. (Genes that are closer together on the chromosome are typically more strongly linked together)

yes

When the new chromosome contains the SAME alleles as originally (it looks like the parent chromosome)

When the new chromosome contains DIFFERENT alleles than originally (it looks different than the parent chromosome)

It is how often linked genes recombine (undergo crossing over)

true

yes

number of recombinants/ total number of progeny

a homozygous recessive organism. (important because only the recessive genes pass on)

1:1:1:1 phenotypic ratio

true

species, age, sex, environment, temperature

recombination across the WHOLE genome

natural selection (provides species with more genetic diversity)

No (they have hotspots and coldspots)

short DNA sequences that repeat in a chromosomal region

It is one of the most common genetic markers. They are substitutions in a SINGLE base pair and each person has a unique set in their genome

They are changes in where restriction enzymes cut DNA at SPECIFIC spots

codominantly

haplotype (it occurs when the SNPs are linked)

Because a certain haplotype is more common in one ethnicity than another which is known as linkage disequilibrium

the way we calculate the probability of two genes being linked

the likelihood CAUSED by linkage / likelihood by independent assortment

the likelihood of linkage for recombination frequencies

complete linkage

complete independent assortment

the theta value

there is likely genetic linkage

there is likely NOT genetic linkage

the test is inconclusive

It finds influential genes across a genome (a gene that can influence a population)

to look for known haplotypes across the genome

Manhatten plots (the higher a dot on a bar the stronger association between a gene and a disease)

They are caused by a single gene change. can be dominant or recessive, and is passed down through families.

changes in number of chromosomes, rearrangements, or changes in large sections of chromosomes

meiotic cell division

Used in specific populations and for some prenatal tests. (those tested do not have symptoms)

Testing for genetic conditions with late age of onset. Ex: Huntington’s Disease

All US states and must be treated within a few weeks of life

detects genetic conditions in a fetus

The specific space in interphase where chromosomes are uncondensed and very active.

are spaces between territories where molecules like enzymes can move. Usually more gene rich chromosomes are closer to the nucleus

karyotypes

their size and shape. (p-short arm and q-long arm)

By Giemsa staining

Regions of chromosomes that are lighter stained. (they are less condensed and more active in gene transcription)

Regions of chromosomes that stain darker. (They are less active in gene regulation and are more condensed)

true

occurs when there are 3+ sets of chromosomes in the nucleus of an
organism

occurs when there is a chromosomal set duplication within a species

happens when chromosomes sets are combined from different species

diploid egg/sperm cells (results in a triploid organism)

doubles chromosome number

the increase in heterozygotes in hybrid lines. (Heterozygotes usually have better resistance to disease)

true

It changes chromosome NUMBER, but not copies of chromosomes

creates a offspring that has monosomes or trisomies

only 2/4 gametes will be affected. 1 will be a trisomy, 1 will be a
monosomy, and 2 will be normal

gene dosage changes

Down syndrome with 3 copies of chromosome. (Caused by the DSCR region of the chromosome)

Turner syndrome and there is only one X chromosome copy only found in females. There is Happloinsufficiency of SHOX gene

when both chromosome copies are from the same parent

when BOTH strands of DNA break at a given point

At the end of the chromosome and include the telomeres

In the MIDDLE of a chromosome and require 2 break points

acentric

micro and macro

whole gene duplication, section of a chromosome deletion

single nucleotide deletion, gene fragment duplication. (the only possible detection is FISH staining)

one recombinant chromosome with a duplication and the other recombinant chromosome with a deletion

when a DNA sequence flips and is read backwards. Ex: the sequence ABCDE can become AEDCB

inversions that occur ONLY on one arm of the chromosome and do not involve the centromere

They are inversions occurring across BOTH arms of the chromosome and involve the centromere

happen when a piece of DNA from one chromosome breaks off and attaches to a different chromosome

occur when pieces of DNA from TWO different chromosomes swap placed. (can play a large role in infertility)

occur when two chromosomes fuse together (therefore the total number of chromosomes in the cell will drop)

histone proteins

The complex the DNA wraps around a histone octomer to form

2 H2A proteins, 2 H2B proteins, 2 H3 proteins, and 2 H4 proteins

When the H1 histone protein binds to the nucleosome DNA and the complex is formed

Chromatosomes that are separated by short pieces of DNA

When chromatin further condenses to form a 30nm fiber

Chromatin condensation helps regulate gene expression, and forming the chromosome shape helps equal chromosome separation in cell division