Kocher BSCI222 Final Exam

threshold characteristic

Characteristic that has only two phenotypes (presence and absence) but whose expression depends on an underlying susceptibility that varies continuously.

frequency distribution

A concise graphical method of summarizing values. In genetics, the phenotypes found in a group of individuals are usually displayed as a frequency distribution. Typically, the phenotypic classes are plotted on the horizontal (x) axis, and the numbers (or proportions) of individuals in each class are plotted on the vertical (y) axis.

normal distribution

Common type of frequency distribution that exhibits a symmetrical, bell-shaped curve; usually arises when a large number of independent factors contribute to a measured value.

quantitative genetics

Genetic analysis of complex characteristics.

meristic characteristic

Characteristic whose phenotype varies in whole numbers, such as number of vertebrae, but may be caused by continuous genetic variation.

regression

Analysis of how one variable changes in response to another variable.

heritability

Proportion of total phenotypic variation that is due to genetic differences. See also broad-sense heritability, narrow-sense heritability.

phenotypic variance

Measure of the degree of phenotypic difference among a group of individuals; composed of genetic, environmental, and genetic-environmental interaction variances.

genetic variance

Component of phenotypic variance that is due to genetic differences among individual members of a population.

environmental variance

Component of phenotypic variance that is due to environmental differences among individual members of a population.

genetic-environmental interaction variance

Component of the phenotypic variance that results from an interaction between genotype and environment. Genotypes are expressed differently in different environments.

additive genetic varience

Component of genetic variance that comprises the additive effects of genes on the phenotype.

dominance genetic variance

Component of genetic variance that can be attributed to dominance (interaction between genes at the same locus).

broad sense heritability

Proportion of phenotypic variance that results from all types of genetic variance.

narrow sense heritability

Proportion of phenotypic variance that results from the additive genetic variance.

quantitative trait locus (QTL)

A chromosomal region containing genes that control polygenic characteristics.

natural selection

Differential reproduction of individuals with different genotypes.

artificial selection

Selection practiced by humans.

response to selection

The extent to which a characteristic subjected to selection changes in one generation; equals the selection differential times the narrow-sense heritability.

selection differential

Difference between the mean phenotype of the selected parents and the mean phenotype of the original population.

realized heritability

Heritability determined by a response-to-selection experiment.

phenotypic correlation

a measure of the strength of the relationship between performance in one trait and performance in another trait

prototrophic

can grow on minimal media

minimal medium

medium containing only inorganic salts, a carbon source, and water

auxotroph

mutant that requires a growth factor

complete medium

contains all the substances required by bacteria for growth and reproduction

plasmid

A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome

episome

A genetic element that can exist either as a plasmid or as part of the bacterial chromosome.

F (fertility) factor

A bacterial extrachromosomal element that allows the bacterium to initiate conjugation. Bacteria that possess the F factor are known as F+ 'males'.

conjugation

A temporary union of two organisms for the purpose of DNA transfer.

transformation

A change in genotype and phenotype due to the assimilation of external DNA by a cell.

transduction

the process where foreign DNA is introduced into a cell via a bacteriophage

pilus

A protein filament that projects from the surface of some prokaryotic cells that facilitates gene transfer

transformant

cell that has received genetic material through transformation

cotransformed

cells that are transformed by two or more genes

horizontal gene transfer

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

restriction modification system

A system used by bacteria to cleave exogenous DNA at specific sites using a restriction endonuclease, and protect the sites on its own DNA by methylation.

Cas proteins

Proteins that function in CRISPR-Cas systems. Combine with crRNA to form an effector complex that cleaves DNA at specific base sequences.

CRISPR-Cas system

a molecular tool used for precise editing of DNA that relies on the action of CRISPR RNAs and Cas proteins

virulent phage

A phage that reproduces only by a lytic cycle.

prophage

A phage genome that has been inserted into a specific site on the bacterial chromosome.

generalized transduction

random bacterial DNA is packaged inside a phage and transferred to a recipient cell

specialized transduction

a highly specific part of the host genome is regularly incorporated into the virus

transducing phage

contains fragments of the host chromosome instead of the viral genome.

transductant

bacterial cell that has received genes from another bacterium through transduction

cotransduced

only genes located close together on the bacterial chromosome will be transferred together

integrase

the enzyme responsible for integrating viral DNA into the host cell's DNA

oncogene

cancer causing gene

antigenetic drift

evolution due to small changes, slower rate (ie influenze and rhinovirus)

nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

chargaff's rules

observed that the amount of A=T and C=G

transforming principle

Substance responsible for transformation. DNA is the transforming principle.

x-ray diffraction

process used by Rosalind Franklin to make images of DNA that helped reveal the structure of DNA

ribose

A five-carbon sugar present in RNA

deoxyribose

A five-carbon sugar that is a component of DNA nucleotides

nitrogenous base

An organic base that contains nitrogen, such as a purine or pyrimidine; a subunit of a nucleotide in DNA and RNA

purine

a nitrogenous base that has a double-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; either adenine or guanine

pyrimidine

a nitrogenous base that has a single-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; thymine, cytosine, or uracil

adenine

The base that pairs with Thymine in DNA and Uracil in RNA; purine

guanine

The base that pairs with Cytosine in DNA; purine

cytosine

nitrogenous base that pairs with Guanine with DNA and is a pyrimidine

thymine

nitrogenous base that pairs with adenine in DNA and is a pyrimidine

uracil

Nitrogen base that pairs with adenine in RNA; pyrimidine

nucleoside

nitrogenous base + sugar

phosphate group

phosphorus atom bonded with four oxygen atoms and part of the sugar-phosphate backbone of DNA

deoxyribonucleotide

Basic building block of DNA, consisting of deoxyribose, a phosphate, and a nitrogenous base.

ribonucleotide

Basic building block of RNA, consisting of ribose, a phosphate group, and a nitrogenous base.

phosphodiester linkage

The connection in a nucleic acid strand, formed by linking two nucleotides.

polynucleotide strand

series of nucleotides linked together by phosphodiester bonds

5' end

the end of the DNA ladder that DNA polymerase is UNABLE to build

3' end

The end of the DNA ladder that DNA polymerase can add nucleotides to during DNA replication; hydroxyl group

antiparallel

referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5' -3' directions).

complementary DNA strands

The relation between the two nucleotide strands of DNA in which each purine on one strand pairs with a specific pyrimidine on the opposite strand (A pairs with T, and G pairs with C).

B-DNA

Right-handed helical structure of DNA that exists when water is abundant; the secondary structure described by Watson and Crick and probably the most common DNA structure in cells.

A-DNA

right-handed helix that is wider and more compact than B-DNA

Z-DNA

Secondary structure of DNA characterized by 12 bases per turn, a left-handed helix, and a sugar-phosphate backbone that zigzags back and forth.

transcription

synthesis of an RNA molecule from a DNA template

translation

Process by which mRNA is decoded and a protein is produced

central dogma

DNA -> RNA -> Protein

reverse transcription

synthesis of DNA from an RNA template

RNA replication

Process in some viruses by which RNA is synthesized from an RNA template.

hairpin

structure of RNA when it folds back on itself and forms intramolecular hydrogen bonds between complementary nucleotides

H-DNA

a rare triple-helical form of DNA that is found in cells. Its function is unknown.

DNA methylation

The addition of methyl groups to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.

5-methylcytosine

modified form of the base cytosine, containing a methyl group (CH3) on the 5' carbon

mitochondrial DNA

DNA found in the mitochondria that is inherited only through mothers

chloroplast DNA

The small genomic component found in the chloroplasts of plants, concerned with photosynthesis and other functions taking place within that organelle.

supercoiling

twisting in the opposite direction to the turns of the double helix during the first stage of mitosis.

relaxed state

No actin-myosin interaction at binding site

Myofilaments overlap a little

positive supercoiling

double helix is overwound

negative supercoiling

DNA is underwound so right-handed supercoil compensates

topoisomerase

corrects "overwinding" ahead of replication forks by breaking, swiveling, and rejoining DNA strands

nucleoid

A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated.

euchromatin

The less condensed form of eukaryotic chromatin that is available for transcription.

heterochromatin

Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.

nonhistone chromosomal protein

one of a heterogeneous assortment of nonhistone proteins in chromatin

nucleosome

repeating subunit of chromatin fibers, consisting of DNA coiled around histones

linker DNA

stretch of DNA separating two nucleosomes

topologically associated domains

Large regions of spatially interacting chromatin. Within a TAD, regions of chromatin lie in close proximity and interact with one another but are separated in space from other TADs. Help to control gene expression in eukaryotic cells.

chromosome puff

Localized swelling of a polytene chromosome; a region of chromatin in which DNA has unwound and is undergoing transcription.