Chapter 11 Notes - Meiosis and Genetics

Codominance

- where both alleles of a gene are expressed completely.

Gametogenesis

- the production of gametes, which includes meiosis and other changes that produce a mature cell.

Codominance

- where both alleles of a gene are expressed completely.

Gametogenesis

- the production of gametes, which includes meiosis and other changes that produce a mature cell.

Fertilization

restores the diploid number in the resulting offspring.

Punnet

square- a grid system for predicting all possible genotypes resulting from a cross.

Barr bodies

- In females, 1 of the 2 X chromosomes is randomly turned by X chromosome inactivation.

Mendel

mated plants with specific traits by removing the male part of flowers, preventing self- pollination and fertilizing female parts with pollen with sperm cells from a different plant, creating hybrids.

DNA

in your body cells is not passed on to your offspring.

Nondisjunction

- when the members of a chromosome pair fail to separate → one gamete receives two of the same type of chromosomes and another gamete receives no copy of that chromosome.

Polygenic traits

- two or more genes interact to influence the phenotype.

Prophase

I- nuclear membrane and nucleolus breaks down, centrioles move to opposite sides of the cell, spindle fibers assemble.

Probability

- the likelihood that a particular event will happen; predicts average.

Chromosome number

does not affect complexity of an organism.

Gametes

- (sex cells) germ cells in your reproductive organs that develop into eggs or sperm.

Recombination

- any mixing of parental alleles.

Telophase

I- the nuclear membrane forms again in some species, spindle fibers disassemble, cell undergoes cytokinesis.

Trisomy

- when the zygote gets three copies of a chromosome.

Meiosis

- a form of nuclear division that divides a diploid cell into haploid cells.

Traits

- distinguishing characteristics that are inherited.

Genetic linkage

- genes located close together tend to be inherited together; genes far apart are more likely to assort independently.

nervous system

Huntington's disease- damages the and appears during adulthood.

Polar bodies

- cells with little more than DNA that are are eventually broken down.

pair of homologous chromosomes

Each gene has a locus- a specific position on a(n) .

Anaphase I

- the paired homologous chromosomes separate from each other and move toward opposite poles of the cell; the sister chromatids remain together.

Carrier

- does not show disease symptoms but can pass on the disease- causing allele.

recessive alleles

Pedigree- a chart that can help trace the phenotypes and genotypes in a family to determine whether people carry .

Genotype

- refers to the genetic makeup of a specific set of genes.

Testcross

- a cross between an organism with an unknown genotype and an organism with the recessive phenotype.

Phenotype

- the physical characteristics of an individual organism.

Multiple alleles

- genes that have more than two possible alleles that can be inherited.

Hybrids

- offspring of crosses between different parents.

Dihybrid

cross- crosses that examine the inheritance of two different traits.

interphase

There is no or DNA replication between the two stages of meiosis.

Blood type

in humans is the result of multiple alleles.

Prophase II

- the nuclear membrane and nucleolus breaks down, centrioles move to opposite poles, spindle fibers assemble.

Telophase II

- nuclear membranes form around each set of chromosomes, spindle fibers break down, nucleolus reforms, cell undergoes cytokinesis.

Haploid cells

- gametes; they have one copy of each chromosome.

X chromosome

has more influence over phenotype.

Gene

- a piece of DNA that provides a set of instructions to a cell to make a certain protein.

fertilization

the actual fusion of an egg and a sperm cell

haploid cells

gametes; they have one copy of each chromosome

Meiosis

a form of nuclear division that divides a diploid cell into haploid cells

Meiosis I

divides homologous chromosomes, producing 2 haploid cells with duplicated chromosomes

Prophase I

nuclear membrane and nucleolus breaks down, centrioles move to opposite sides of the cell, spindle fibers assemble

Metaphase I

the homologous chromosome pairs are lined up along the middle of the cell by spindle fibers

Anaphase I

the paired homologous chromosomes separate from each other and move toward opposite poles of the cell; the sister chromatids remain together

Telophase I

the nuclear membrane forms again in some species, spindle fibers disassemble, cell undergoes cytokinesis

Meiosis II

divides sister chromatids and results in unpaired chromosomes

Prophase II

the nuclear membrane and nucleolus breaks down, centrioles move to opposite poles, spindle fibers assemble

Metaphase II

spindle fibers align the 23 chromosomes at the cell equator

Anaphase II

sister chromatids are puled apart from each other and move to opposite poles of the cell

Telophase II

nuclear membranes form around each set of chromosomes, spindle fibers break down, nucleolus reforms, cell undergoes cytokinesis

traits

distinguishing characteristics that are inherited

genetics

the study of biological inheritance patterns and variation in organisms

hybrids

offspring of crosses between different parents

cross

the mating of two organisms

gene

a piece of DNA that provides a set of instructions to a cell to make a certain protein

allele

any of the alternative forms of a gene that may occur at a specific locus

homozygous

two of the same alleles at a specific locus; identical to each other

heterozygous

two different alleles at a specific locus

genome

all of an organism's genetic material

genotype

refers to the genetic makeup of a specific set of genes

phenotype

the physical characteristics of an individual organism