Genetics Flashcards

helicase

unwinds the DNA strands on both sides of the replication bubble

SSBs

keep the replication bubble open

topoisomerase

relieves the tension/supercoiling upstream of the replication bubble

primase

adds RNA primers

DNA Polymerase III

adds DNA to the end of the RNA primers in the 3’ to 5’ direction

DNA Polymerase I

replaces RNA with DNA in okizaki fragments

DNA Ligase

joins the okizaki fragments by catalyzing the formation of phosphodiester bonds

transcription

from DNA to mRNA

translation

from RNA to protein

introns

sections that will be removed from mRNA (the commerical breaks)

exons

sections that will be translated from mRNA to protein (the actual TV show)

purines - adenine and guanine

nitrogenous bases that have 5 + 6 membered rings

pyrimidines - cytosine, thymine, uracil

nitrogenous bases with one 6 membered ring

anticodon

3 base pairs on a tRNA molecule that are complementary to the strand of mRNA that codes for a particular amino acid

southern blotting

transfers DNA from gel electrophoresis onto a permanent membrane

northern blotting

transfers mRNA from gel electrophoresis onto a permanent membrane

western blotting

transfers proteins from gel electrophoresis onto a permanent membrane

molecular probe

bind to and locate specific proteins or nucleic acid sequences (complementary strands or antibodies can be used)

hybridization

uses single stranded complementary nucleic acids to locate a specific sequence

silent mutation

mutation where the mutated codon codes for the same amino acid as the wild type

missense mutation

mutation where the mutated codon codes for a different amino acid than the wild type

nonsense mutation

mutation where the mutated codon is a stop codon, often resulting in short, dysfunctional proteins

frameshift mutation

mutation where a nucleotide pair is inserted or deleted, shifting the entire sequence by one. If this happens in any multiple of 3, it is called a codon insertion/deletion

PCR

chain reaction that can be used to amplify a small amount of DNA. Uses 1) denaturation, 2) primer annealing and 3) primer extension

monohybrid cross

cross between two heterozygous parents (Gg x Gg)

test cross

cross of a dominant phenotype organism w/heterozygous recessive to determine the organism’s genotype by observing the ratio of progeny traits

Haplosufficient

A term describing a wild type allele for which one copy is sufficient enough to produce the dominant phenotype in heterozygous individuals

Haploinsufficient

A term describing a wild type allele for which one copy is not sufficient enough to produce the dominant phenotype in heterozygous individuals

Loss of Function Mutation

A mutation that causes a significant loss or elimination of functional activity of a gene product (when compared with the wild-type)

Gain of Function Mutation

A mutation that causes a significant increase of functional activity of a gene product (when compared with the wild-type)

Null/Amorphic Mutation

A loss of function mutation that results in a complete loss of gene function. These are often lethal in the homozygous genotype

Leaky/Hypomorphic Mutation

A loss of function mutation that results in only a partial loss of gene function. These can be, but are not always, lethal in the homozygous genotype

Dominant negative mutation

A loss of function mutation for which the mutated gene is dominant over the wild type

Hypermorphic Mutations

gain of function mutations that induce an excess of gene activity which can push processes forward at the wrong time and/or for longer than normal. They often affect regulatory genes.

Neomorphic Mutations

Gain of function mutations in which the mutated genes aquire novel gene activities which cause them to have functional structures that operate differently than the wild type ones. They are usually dominant

Incomplete/Partial Dominance

Heterozygous organisms fall somewhere on the middle of the spectrum between the type phenotypes i.e. progeny of red and white flowers is pink

Codominance

Heterozygous organisms display both phenotypes (meaning they are not mutually exclusive) i.e. progeny of red and white flowers are both white and red

Allelic Series

The number of possible alleles for a gene in a given population. Alleles may display a variety of dominance relationships with each other. Ex. The I^A, I^B and i genes for blood type

Complete penetrance

Every organism carrying a specific genotype will also have the associated phenotype

Sex Limited Traits

Traits for which both sexes carry the genes for a specifc trait, but the trait is only expressed in one sex i.e. horns in hoofed mammals

Sex Influenced Traits

Traits for which the inheritance pattern differs between the sexes, even when the genotype is the same i.e. the bearded sheep

Incomplete penetrance

Not all organisms with the genotype for the trait actually express the corresponding phenotype, even if the trait is dominant

Variable expressivity

the same genotype produces phenotypes that vary in their degree or form of expression

pleiotropy

Multiple effects are caused by a single mutation i.e. a mutation in a single gene in cats effects fur color, eye color AND tail length

gene interaction

the collaboration of multiple genes in the production of a single phenotype (or group of related characteristics)

anabolic pathway

pathway that synthesizes something, such as a protein

catabolic pathway

pathway breaks down complex molecules

Genetic Dissection

An experimental approach that separately tests the ability of a mutant to execute each step of a biosynthetic pathway, thereby determining the steps of the pathway and which step is blocked in each mutant

Epistatis

When one gene affects, masks or modifies the effects of another gene.

Complementary Gene Interaction

two genes are needed to produce a single product. For example, two genes are needed produce the purple pigment in the flower of sweet peas. 9:7 ratio

Duplicate Gene Action

two genes duplicate one another’s activity, creating a redundant genetic system in which any genotype possessing at least one copy of the dominant allele at either locus will produce the dominant phenotype. 15:1 ratio

Dominant Gene Interaction

a dominant allele at either of two genes produces the same phenotype, but having dominant alleles at both genes together produces a new phenotype. 9:6:1 ratio

Recessive Epistasis

a type of epistasis in which the homozygous recessive genotype at one gene (aa) masks the expression of a second gene. 9:3:4 ratio

Dominant Epistasis

a dominant allele at one gene masks the expression of a second gene. 12:3:1 ratio

Dominant Suppression

a type of epistasis in which a dominant allele at one gene suppresses the expression of a second gene, producing a characteristic 13:3 phenotypic ratio in a dihybrid cross.

genetic heterogeneity

mutations of different genes can produce the same abnormal phenotype

genetic complementation analysis

an experimental analysis of crosses designed to test whether the same mutant phenotype in different populations is caused by mutations on the same or different genes

complementation group

a group of mutant alleles for the same gene, which will fail to complement each other but will complement members of other groups

Synapsis

The pairing of homologous chromosomes along their lengths during zygotene of Prophase I

Synaptonemal Complex

A protein structure that hold homologous chromosomes together while they pair

Bivalent/Tetrad

A structure formed when two homologous chromosomes are paired together during meiosis. Each chromosome has 2 sister chromatids, so there are 4 chromatids total

Chiasmata

The visible, physical points where homologous chromosomes remain attached after crossing over

Terminalization

The movement of chiasmata towards the chromosome ends during diakinesis

Pachytene

During which stage of prophase I would you expect to see nuclear membrane breakdown, synaptonemal complex fully formed and crossing over between nonsister chromatids of homologous chromosomes?

Zygotene

During which substage of Prophase I do homologous chromosomes first undergo synapsis and begin forming the synaptonemal complex?

Diplotene

During which substage of Prophase I does the synaptonemal complex disappear while homologous chromosomes begin separating but remain attached at chiasmata?

Diakinesis

Which substage of Prophase I is characterized by maximum chromosome condensation, terminalization of chiasmata, and nuclear envelope breakdown?

UAA, UAG, UGA

stop codons