HOSA ILC Genetics

cell cycle

The continuous series of events in which a cell grows, copies its DNA, prepares for division, and divides into daughter cells

interphase

The longest stage of the cell cycle in which the cell grows, carries out normal functions, replicates DNA, and prepares for division; includes G1, S, and G2 phases

G1 phase

The first growth phase of interphase in which the cell increases in size, performs normal metabolic activities, and duplicates organelles

S phase

The synthesis phase of interphase during which DNA is replicated so each chromosome consists of two sister chromatids

G2 phase

The second growth phase of interphase in which the cell checks replicated DNA, repairs errors, and prepares for mitosis

mitosis

A form of nuclear division producing two genetically identical diploid daughter cells

meiosis

A two-stage form of cell division that produces four genetically unique haploid gametes from one diploid parent cell

cytokinesis

Division of the cytoplasm that physically separates one cell into two daughter cells

chromosome

A condensed structure made of DNA and proteins that carries genetic information

chromatid

One half of a duplicated chromosome joined to its identical copy at the centromere

sister chromatids

Identical copies of a chromosome connected by a centromere after DNA replication

centromere

The region of a chromosome where sister chromatids are attached and spindle fibers bind

centriole

A cylindrical structure in animal cells that helps organize spindle fibers during cell division

spindle fibers

Microtubule structures that move chromosomes during mitosis and meiosis

diploid

A cell containing two sets of chromosomes, represented as 2n

haploid

A cell containing one set of chromosomes, represented as n

gamete

A haploid reproductive cell such as sperm or egg

somatic cell

A body cell that is not directly involved in reproduction

homologous chromosomes

A pair of chromosomes with the same genes at corresponding locations, one inherited from each parent

prophase

The first stage of mitosis in which chromosomes condense, spindle fibers form, and the nuclear membrane breaks down

metaphase

The stage of mitosis where chromosomes line up along the metaphase plate in the center of the cell

metaphase plate

The imaginary line across the middle of the cell where chromosomes align during metaphase

anaphase

The stage of mitosis in which sister chromatids separate and move toward opposite poles

telophase

The final stage of mitosis in which chromosomes decondense and nuclear membranes reform

prophase I

The first stage of meiosis I during which homologous chromosomes pair and crossing-over occurs

metaphase I

The stage of meiosis I where tetrads line up along the metaphase plate

anaphase I

The stage of meiosis I in which homologous chromosomes separate to opposite poles

telophase I

The stage of meiosis I in which two haploid cells begin forming

prophase II

The beginning of meiosis II where chromosomes condense and spindle fibers form again

metaphase II

The stage of meiosis II in which chromosomes align individually at the cell center

anaphase II

The stage of meiosis II in which sister chromatids separate

telophase II

The final stage of meiosis II that produces four haploid daughter cells

recombination

The exchange of genetic material between homologous chromosomes that increases genetic diversity

crossing-over

The swapping of DNA segments between non-sister chromatids during prophase I of meiosis

tetrad

A structure formed when homologous chromosomes pair during meiosis I, containing four chromatids

independent assortment

The random orientation and separation of homologous chromosome pairs during meiosis

nondisjunction

Failure of chromosomes or chromatids to separate properly during cell division

trisomy

A chromosomal condition in which an individual has three copies of a chromosome instead of two

monosomy

A chromosomal condition in which one chromosome is missing from a pair

polyploid

Having more than two complete sets of chromosomes

mutation

A permanent change in the DNA sequence

gene

A segment of DNA that codes for a functional product such as a protein

allele

An alternative form of a gene

genotype

The genetic makeup of an organism represented by allele combinations

phenotype

The observable traits or characteristics of an organism

dominant allele

An allele that is expressed whenever it is present

recessive allele

An allele expressed only when no dominant allele is present

homozygous

Having two identical alleles for a gene

heterozygous

Having two different alleles for a gene

Mendel’s law of dominance

The principle stating that dominant alleles mask recessive alleles in heterozygotes

Mendel’s law of segregation

The principle stating that allele pairs separate during gamete formation

Mendel’s law of independent assortment

The principle stating that genes for different traits assort independently during gamete formation

Punnett square

A diagram used to predict the outcomes of genetic crosses

monohybrid cross

A genetic cross involving one trait

dihybrid cross

A genetic cross involving two traits

FOIL method

A strategy used to determine all possible gamete combinations in a dihybrid cross

P generation

The parental generation in a genetic cross

F1 generation

The first filial generation produced from the parental cross

F2 generation

The offspring produced by crossing members of the F1 generation

incomplete dominance

A pattern of inheritance in which heterozygotes show an intermediate phenotype

codominance

A pattern of inheritance in which both alleles are fully expressed in heterozygotes

multiple alleles

The existence of more than two allele forms for a gene within a population

ABO blood group

A blood typing system determined by IA, IB, and i alleles

Rh factor

An inherited blood protein that determines positive or negative blood type

sex-linked trait

A trait controlled by genes located on sex chromosomes

X-linked inheritance

Inheritance of genes located on the X chromosome

pedigree

A diagram used to trace the inheritance of traits through generations

autosomal trait

A trait determined by genes on non-sex chromosomes

carrier

An individual who possesses a recessive allele without expressing the trait

karyotype

An organized visual display of chromosomes arranged by size and shape

aneuploidy

An abnormal chromosome number due to nondisjunction

Down syndrome

A genetic disorder caused by trisomy 21

Turner syndrome

A disorder in females caused by monosomy X

Klinefelter syndrome

A chromosomal disorder in males caused by an extra X chromosome (XXY)

recombination frequency

The percentage of recombinant offspring produced between two genes

gene mapping

Determining the relative locations of genes on chromosomes

linked genes

Genes located close together on the same chromosome that tend to be inherited together

chi-square analysis

A statistical test used to compare observed results with expected results

null hypothesis

A prediction that there is no significant difference between observed and expected data

probability

The likelihood that an event will occur

standard deviation

A measure of variation around a mean

control group

The part of an experiment that does not receive the independent variable

independent variable

The factor deliberately changed in an experiment

dependent variable

The factor measured in an experiment

model organism

A species used to study biological processes due to ease of research and genetic similarity

Drosophila melanogaster

The fruit fly commonly used in genetics research

Wisconsin Fast Plants

Rapid-cycling plants used for genetics and life cycle experiments

zebrafish

A transparent vertebrate model organism used in developmental genetics

yeast

A unicellular fungus frequently used in molecular genetics research

plasmid

A small circular DNA molecule in bacteria capable of independent replication

bacterial conjugation

Transfer of genetic material between bacteria through direct contact

pilus

A hair-like bacterial structure involved in conjugation

antibiotic resistance

The ability of bacteria to survive exposure to antibiotics

transduction

Transfer of bacterial DNA by a bacteriophage

bacteriophage

A virus that infects bacteria

lytic cycle

Viral replication cycle that destroys the host cell by lysis

lysogenic cycle

Viral cycle in which viral DNA integrates into the host genome and remains dormant

prophage

Viral DNA integrated into a bacterial chromosome

generalized transduction

Random transfer of bacterial DNA by a bacteriophage

specialized transduction

Transfer of specific bacterial genes adjacent to prophage insertion sites