Meiosis and Genetics Review Flashcards

These flashcards summarize key terms and concepts from the lecture on meiosis and genetics, covering definitions, principles, and examples.

Meiosis

A type of cell division that reduces the chromosome number by half, producing four haploid cells.

Tetrad

A structure containing four chromatids formed during meiosis.

Fertilization

The process by which a sperm and egg cell combine to form a zygote.

Embryo

An early stage of development in sexually reproducing organisms after fertilization.

Gametes

Reproductive cells (sperm and egg) that are haploid.

Zygote

The fertilized egg that results from the union of sperm and egg.

Homologous chromosomes

Chromosome pairs, one from each parent, that are similar in shape and size.

Autosomes

Chromosomes that are not sex chromosomes.

Sex chromosomes

Chromosomes that determine the sex of an organism.

Haploid

A cell that has half the number of chromosomes, typically seen in gametes.

Diploid

A cell with two complete sets of chromosomes, one from each parent.

Crossing-over

The exchange of genetic material between homologous chromosomes during meiosis.

Nondisjunction

An error in meiosis where homologous chromosomes fail to separate properly.

Gene

A segment of DNA that codes for a protein and determines a trait.

Alleles

Different forms of a gene that can exist at a specific locus.

Recessive

An allele that is not expressed in the phenotype unless two copies are present.

Dominant

An allele that is expressed in the phenotype even if only one copy is present.

Genotype

The genetic makeup of an individual, represented by alleles.

Phenotype

The physical expression or characteristics of a genotype.

Homozygous

An organism with two identical alleles for a trait.

Heterozygous

An organism with two different alleles for a trait.

Karyotype

A display of an individual's complete set of chromosomes.

Incomplete dominance

A form of inheritance where the phenotype is a blend of the two parental traits.

Codominance

A form of inheritance where both alleles in the genotype are expressed in the phenotype.

Sex-linked genes

Genes located on sex chromosomes, often leading to traits that are inherited differently in males and females.

Polyallelic

A trait that is controlled by multiple alleles.

Polygenic traits

Traits that are controlled by two or more genes.

Gregor Mendel

The father of genetics known for his work on inheritance patterns.

Law of segregation

Mendel's principle that states allele pairs separate during gamete formation.

Law of independent assortment

Mendel's principle stating that genes for different traits assort independently of one another.

Pedigree chart

A diagram that depicts the biological relationships between individuals in a family.

Punnett square

A grid used to predict the possible genotypes of offspring from parental alleles.

Carrier

An individual who carries one copy of a recessive allele for a trait.

Purebred

An organism that has two identical alleles for a trait.

Generation (P, F1, F2)

Stages in the breeding process where P is parental, F1 is first generation, and F2 is second generation.

Trait

A characteristic that an organism can pass on to its offspring.

Heredity/inheritance

The passing of traits from parents to offspring.

Haploid vs Diploid

Haploid cells have one set of chromosomes (n), while diploid cells have two sets (2n); humans have 23 haploid chromosomes and 46 diploid chromosomes.

Karyotype information

A karyotype shows the number and appearance of chromosomes but does not show specific gene sequences.

Nondisjunction defined

Nondisjunction occurs when chromosomes fail to separate correctly during cell division.

Mitosis vs Meiosis

Mitosis results in two identical diploid cells, while meiosis results in four genetically diverse haploid cells.

Reproductive cells

Cells that are involved in sexual reproduction, namely gametes.

Meiosis necessity

Meiosis is necessary for sexual reproduction as it produces gametes.

Homologous chromosomes defined

Chromosomes that pair during meiosis and have similar genes.

Tetrads and chromatids

Tetrads consist of homologous chromosomes paired together, each made of two sister chromatids.

Crossing-over and genetic diversity

Crossing-over exchanges genetic material between chromosomes, increasing genetic diversity.

Meiosis end cells

Meiosis produces four haploid cells that are genetically distinct.

Genotype vs Phenotype

Genotype is the genetic makeup, while phenotype is the observable traits; they are linked through gene expression.

Sex-linked traits in females

Females have two X chromosomes, reducing the likelihood of expressing X-linked disorders.

Multiple alleles defined

Multiple alleles refer to the existence of more than two possible alleles for a gene, e.g., human blood type.

Carrier definition

A carrier is an individual who possesses one recessive allele for a trait but does not express it.

Polygenic trait definition

A trait controlled by multiple genes, leading to a continuum of phenotypes.

Codominance example

An example of codominance is AB blood type in humans where both A and B alleles are expressed.

Incomplete dominance example

An example of incomplete dominance is a red flower crossed with a white flower producing pink offspring.