cell division Flashcards
a section of the DNA that for a particular physical characteristic (trait)
gene
the collection of genes that an individual carries in their cells
genome
DNA tightly coiled during cell division
chromosomes
A massive, uncoiled, DNA and associated proteins
chromatin
(body cells) have two copies of each chromosome
somatic cells
(Reproductive cells: sperm/egg) have half as many chromosomes as somatic cells
gametes
The process of division of a cell nucleus. Produces two daughter cells genetically identical to the parent cell.
mitosis
Division of the rest of the cell contents
cytokinesis
Chromatin coils, tightly to form chromosomes, duplicate chromosomes appear as paired sister chromatids attached to the centromere, Nuclear membrane disintegrates, and spindle fibers form.
prophase
Chromosomes lined up on the equator of the cell.
metaphase (middle)
Spindle fibers pull apart sister chromatids, which begin to move to opposite ends of the cell.
anaphase
The cell begins to divide into two, chromosomes uncoil, nucleus reforms, and spindle apparatus disassembles.
telophase
Produces offspring with the genetic material of one pair only, offsprings genuinely identical to parent. Common in plants, single celled organisms, fungi, and some animals.
asexual reproduction
Cell division, that leads to the production of gametes.
Meiosis
Combination of genetic material from different individuals
Sexual reproduction
A cell with one copy of each gene
Diploid
Same size and function
Homologus pair
Do not belong to the same pair
nonhomologous chromosomes
cell that has pairs of homologous chromosomes, 1 from each parent
Diploid cells
Homologous pairs at equator, homologous split, (reduction, division)
Meiosis one
Sister chromatids, lineup duplicates split
Meiosis two
homologous chromosomes pair up (tetrad), nuclear membrane dissolves
meiosis one: prophase one
Areas where homologous chromosomes crossover one another
chiasm
Physical exchange of parts of non-sister, chromatids, produces recombinant chromosomes, and adds genetic variability.
meiosis one: crossing over
When homologous chromosomes exchange, genetic material through the process, called chromosomal crossover. Can result in different combinations of genes than the parents.
recombinant chromosomes
Homologous pairs, line up at the center of the cell, look like a bundle of four sticks called tetrads
meiosis one: metaphase one
homologous chromosomes separate and are pulled to opposite sides of the cell
meiosis one: anaphase one
Daughter cells separate, each new nucleus is now haploid, and sister chromatids are not necessarily identical, because of crossing over
Meiosis one: telophase one
a. Produces two cells identical to each other.
b. Produces haploid cells that are not identical to each other. this is from crossover and random alignment.
match: meiosis & mitosis
a. mitosis
b. meiosis
Version of a gene, most genes have two or more variance that can describe the same trait. Example: purple flowers vs white flowers.
Allele
Only way to get the same type of offspring from the parent, because they only have one
true breeding
The variation of a gene that is always expressed if it is present. Denoted by a capital letter.
dominant
A gene variant that is only expressed if there are two copies. Denoted by a lowercase letter.
recessive
Having two copies of the same allele. example: BB/bb
homozygous
having two different alleles for a gene. example: Bb
Heterozygous
Genetic make up of an organism (set of alleles)
genotype
Physical expression of the genes
Phenotype
P is what
Parental generation
F 1 is what
Hybrid offspring
F 2 is what
Offspring of F1 generation
When multiple genes control a single trait, the common phenotype is an accumulation of contributions by multiple genes. These traits show continuous variation.
Polygenic inheritance
One allele has more than one affect on the phenotype
pleiotropy
dominant allele doesn’t completely suppress the recessive, so an intermediate phenotype is expressed
Incomplete dominant
Both alleles are expressed in the heterozygous, and the phenotype has characteristics of each
Codominance
Expression of one gene alters the expression of a second gene
epistasis
Abnormal chromosome number in the gamete, resulting from pairs of homologous chromosomes that do not separate normally during meiosis.
Nondisjunction
an abnormal number of a particular chromosome
aneuploidy
Having more than two complete sets of chromosomes
polyploidy
triploid
3n
tetraploid
4n
Environmental or lifestyle factors can modulate gene expression, turning genes off or on.
epigenetic
Mitochondria and chloroplast are copied as cells need more energy. have their own separate DNA.
extranuclear genes
