46 terms

Chapter 6: Meiosis & Genetics

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Somatic cells
cells that make up the tissues of your body; aka body cells
Gametes
sex cells; eggs & sperm
homologous chromosomes
chromosomes that have copies of the same genes; one is inherited from the father and one from the mother
autosomes
chromosomes that contain genes that are not directly related to the sex of an organism
sex chromosomes
chromosomes that directly control the development of sexual characteristics; males have XY and females have XX
sexual reproduction
involves the fusion of two gametes taht resutls in offspring that are a unique genetic mixture of both parents
diploid
cells that have two copies of each chromosome; body cells
haploid
cells that have only one copy of each chromosome; gametes
meiosis
form of cell division that divides a diploid cell into haploid cells; used to make eggs & sperm
prophase 1
stage where nuclear membrane breaks down, spindle forms and homologous chromosomes pair up
metaphase 1
stage where homologous chromosomes line up in the middle of the cell
anaphase 1
stage where homologous chromosomes are separated and move to opposite ends of the cell
telophase 1
stage where nuclear membranes form around each set of chromosomes; cytokinesis begins & creates 2 diploid cells
prophase 2
stage where nuclear membranes break down and the spindle fibers form (happening in 2 cells at the same time)
metaphase 2
stage where chromosomes are lined up in the middle of the cell
anaphase 2
stage where the sister chromatids of each chromosome are separated and move to opposite ends of the cell
telophase 2
stage where nuclear membranes form around each set of chromosomes & the spindle dissolves; cytokinesis begins, creating 4 haploid cells
gametogenesis
production of gametes (through the process of meiosis)
sperm cell
male gamete
egg cell
female gamete
polar bodies
extra cells that are created during egg formation in females that are broken down by the body; the cells do not become egg cells
traits
distinguishing characteristics that are inherited; ex. hair color, eye color
genetics
the study of biological inheritance patterns and variations in organisms
purebred
organism that creates offspring that are just like the parent; homozygous dominant genotype
hybrid
organism that creates offspring that are different from the parent; heterozygous genotype
cross
the mating of two organisms
law of segregation
law of genetics that states:
1) each organism inherits 2 copies of each gene, one from each parent
2) organisms donate only one copy of their genes to their offspring
gene
a region of DNA that provides a set of instructions to a cell to make a certain protein; a region of DNA that codes for a particular trait
allele
any alternative of a specific gene
homozygous
an organism that has the same alleles for a particular trait; ex. AA or aa
heterozygous
an organism that has different alleles for a particular trait; ex. Aa
homozygous dominant
an organism that has two dominant alleles for a particular trait; ex. AA or BB
homozygous recessive
an organism that has two recessive allelles for a particular trait; ex. aa or bb
genome
all of an organism's genetic material
genotype
refers to an organism's genetic makeup (the type of alleles) of a particular trait; designated by letters; ex. AA, Aa, aa
dominant allele
the allele that creates the physical trait (expressed) when two different alleles are present; denoted by a capital letter
recessive allele
the allele that creates the physical trait (expressed) only when two copies of the allele are present; denoted by a lowercase letter
phenotype
the physical trait that is expressed; ex. eye color, hair color
Punnett Square
grid system that is used to predict all possible genotypes resulting from a cross of two organisms
monohybrid cross
a genetic cross that examines the inheritance of only one trait
dihybrid cross
a genetic cross that examines the inheritance of two traits
testcross
a genetic cross that is used to determine the genotype of an organism; it always involves crossing the unknown genotype wit the homozygous recessive genotype
law of independent assortment
states that allele pairs separate independently of each other during meiosis; aka different traits appear to be inherited separately
probability
the likelihood that a particular event will happen; used to predict the inheritance of certain genes
crossing over
the exchange of chromosome segments between homologous chromosomes during prophase 1; aka homologous chromosomes swap pieces of DNA
genetic linkage
genes located close together on a chromosome tend to be inherited together