exam 2 genetics Flashcards
Gene
DNA sequence producing a particular product (protein) or influencing activity of another gene
Alleles
Alternate versions of a gene
Chromosome
One molecule of DNA
Genome
Full DNA code
Locus
Location of a gene in the genome
Ploidy
Number of copies of each gene or chromosome
Diploid
two copies (2n)
Haploid
one copy (n) Bacteria
Homologous chromosomes
“Matching” chromosomes in 2n or greater cells
Chare genes but may differ in alleles
Sister chromatids
Identical copies of one chromosome
Centromere
Where sister chromatids are joined together
Mitosis
Eukaryotic
Cell duplication
Identical genome
No change in ploidy (2n to 2n)
Meiosis
Eukaryotic
Genomes differ
Halved ploidy (2n to n)
Binary Fission
Prokaryotes
Cell duplication
No change in ploidy (n to n)
Mitosis in diploids
Chromosomes duplicate to form sister chromatids
Homologous chromosomes line up independently
Chromatids separate for cell division
Each daughter cell is diploid with ~identical genome
Binary Fission in prokaryotes
Haploid genome
Circular chromosome replicates
Cell division occurs to produce two cells
Each daughter cell is haploid with ~identical genome
meiosis
homologous chromosomes pair up and separate in first division.
cells divide again.
four haploid cells result.
independent assortment
for genes on different chromosomes, alleles sort into gametes at random.
linked genes
for genes on the same chromosome, alleles do not sort at random.
recombination via crossover
during meiosis homologous chromosomes may swap fragments.
crossing over breaks linkage allowing different allele combinations on a chromosome.
recombination frequency
increased distance between linked genes increases chance of crossover
