bio 121 midterm 1

DNA (deoxyribonucleic acid)

• nucleotides with bases A, C, G, T

• forms genes (store information long-term)

mRNA (messenger RNA)

• nucleotides with bases A, C, G, U

• temporary message to transmit information

proteins

• amino acids

• does work in cells

gene

a segment of DNA that contains the information required to produce a product that functions in the organism

allele

different versions of a gene that have slight variations in the DNA sequences found in other alleles of the same gene

transcription

process that creates an RNA molecule from information stored in a gene

translation

process that uses the infromation in messenger RNA (mRNA) to synthesize a protein

gene expression

the set of processes that results in using the information stored in a gene

chromatin

complex of DNA + histones = chromosome

nucleosome

group of 8 histone proteins that has DNA wrapped around it

histone proteins

proteins that have an abundance of + lysines & arginines in primary structure, interact with - charges on sugar-phosphate backbone of DNA to form nucleosomes

haploid number

number of different types of chromosomes in a cell (n)

ploidy

number of copies of each type of chromosome in a cell (number before n)

haploid

one of each type of chromosome in a cell (ploidy)

diploid

two of each type of chromosome in a cell (ploidy)

homozygous

individuals with 2 copies of the same allele of a gene

heterozygous

individuals with 2 different alleles at a gene

dominant allele

the allele with a phenotype that appears in heterozygous individuals

recessive allele

the allele with a phenotype that does not appear in heterozygous individuals

phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment

genotype

specific sequence of bases in genes

mutation

any random change in base sequence of DNA that can change the genotype and phenotype

co-dominant allele

heterozygous individuals express the phenotype associated with both alleles

autosomes

other 22 chromosomes other than sex chromosomes in humans

discrete states

when alleles for traits are from single genes

polygenic traits

traits that show continuous and normally distributed variation instead of discrete states

the polygenic model

1. many genes involved

2. effects of each allele add up

genome

entire collection of genes in an individual

loci (locus)

individual locations in a genome

metabolism

chemical reactions and other processes that are required to take in resources and process them in ways that make growth and reproduction possible

mitosis

process in eukaryotes where a copy of each chromosome is distributed to each daughter cell. occurs after replication of chromosomes, prior to cell division

prophase

• replicated chromosomes condense

• nuclear envelope breaks apart

metaphase

replicated chromosomes move to middle of cell

anaphase

sister chromatids separate to become independent chromosomes and move to opposite ends of the cell

telophase

nuclear envelopes reform around each set of chromosomes

cell division

splits parent cell into two daughter cells, each with a complete set of identical chromosomes

DNA replication

creates replicated chromosomes

m phase

portion of cell cycle where mitosis & cell division occur

interphase

portion of cell cycle where growth & DNA replication occur

germ cells

cells that directly give rise to sperm/eggs, or sperm/eggs themselves. undergo meiosis to produce haploid daughter cells

somatic cells

cells that form body, only undergo mitosis

meiosis

a process in eukaryotes that distributes one of each homologous chromosome pair to daughter cells, resulting in a halving of chromosome number

gamete

cells that fuse to form a zygote (sperm & egg)

zygote

fertilized egg

crossing over and recombination

physical exchange of DNA strands between non-sister chromatids during meiosis I. leads to recombinant chromosomes containing alleles from both maternal & paternal chromosomes

sexual reproduction

production of offspring based on meiosis & fusion of gametes

asexual reproduction

production of offspring based on mitosis

independent assortment

maternal and paternal homologs line up at random before separating at the end of Meiosis I, producing a wide array of possible combinations in daughter cells