genetics and heredity

proteins

macromolecules made of amino acids that perform structural, functional, and regulatory roles

lipids

organic molecules involved in energy storage, cell membranes, and signaling

carbohydrates

organic molecules used for energy storage and structural functions

nucleic acids

macromolecules including dna and rna that store and transmit genetic information

prokaryotic cell

a cell without a nucleus or membrane-bound organelles

eukaryotic cell

a cell containing a nucleus and membrane-bound organelles

nucleus

organelle containing most of a cell’s dna

mitochondria

organelles responsible for producing much of the cell’s usable energy

ribosome

cellular structure responsible for protein synthesis

dna

deoxyribonucleic acid that stores hereditary information

rosalind franklin

scientist whose x-ray diffraction research provided important evidence about the structure of dna

amino acids

small molecules that combine to form proteins

gene

a segment of dna containing information for a functional product or hereditary characteristic

chromosomes

structures made of dna and proteins that carry genetic information

dna polymerase

enzyme that builds new dna strands during dna replication

somatic cell

any body cell other than a reproductive cell

homologous chromosomes

paired chromosomes containing the same genes at corresponding locations

diploid

having two complete sets of chromosomes

haploid

having one complete set of chromosomes

sister chromatids

identical copies of a replicated chromosome

gametes

haploid reproductive cells

genetic recombination

the rearrangement of genetic material that creates new combinations of alleles

autosomes

chromosomes other than the sex chromosomes

transcription

process of copying genetic information from dna into rna

translation

process of using mrna information to build a protein

rna

ribonucleic acid involved in carrying and expressing genetic information

dna

the molecule that stores hereditary information and provides instructions for protein production

messenger rna

RNA molecule that carries genetic instructions from dna to the ribosome

transfer rna

RNA molecule that carries amino acids to the ribosome during translation

codon

three-nucleotide sequence in mrna that specifies an amino acid or stop signal

sex chromosomes

chromosomes associated with biological sex and containing sex-linked genes

locus

specific location of a gene on a chromosome

mutation

a change in the dna sequence

genotype

the genetic makeup of an individual

phenotype

observable characteristics produced by genetic and environmental influences

karyotype

organized display of an individual’s chromosomes

polyploidy

possession of more than two complete sets of chromosomes

aneuploidy

abnormal number of individual chromosomes

dispermy

fertilization of an egg by two sperm

nondisjunction

failure of chromosomes or chromatids to separate properly during cell division

dominant

an allele whose effect is expressed when present in a heterozygote

recessive

an allele whose effect is generally expressed when two copies are present

heterozygous

having two different alleles at a locus

homozygous

having two identical alleles at a locus

punnett square

diagram used to predict possible offspring genotypes and phenotypes

x-linked

a trait controlled by a gene located on the x chromosome

autosomal

referring to a gene located on an autosome

polygenic traits

traits influenced by multiple genes

penetrance

the proportion of individuals with a particular genotype who express the associated phenotype

viable offspring

offspring capable of surviving

fertile offspring

offspring capable of reproducing

two purposes of dna

dna stores hereditary information and provides instructions for producing functional products

structure of dna

dna consists of two antiparallel nucleotide strands forming a double helix with complementary base pairing

dna replication

dna is copied before cell division using each original strand as a template; this is called semiconservative replication

protein synthesis

transcription produces mrna from dna and translation uses mrna to build proteins

types of mutations

the basic types include substitutions, insertions, and deletions

frameshift mutation

an insertion or deletion that changes the reading frame of a gene

human chromosome number

humans normally have 46 chromosomes organized into 23 pairs

mitosis

cell division that produces two genetically similar diploid cells for growth, repair, and replacement of somatic cells

meiosis

cell division that produces haploid reproductive cells with genetically different chromosome combinations

meiosis in males

one primary reproductive cell produces four functional sperm cells

meiosis in females

one primary reproductive cell produces one functional egg and polar bodies

crossing over

exchange of genetic material between homologous chromosomes during meiosis that increases genetic variation

mendel’s hypothesis

traits are controlled by discrete hereditary factors that are passed from parents to offspring rather than blending

mendel’s single-trait crosses

demonstrated that traits are controlled by pairs of hereditary factors and led to the law of segregation

law of segregation

the two alleles for a gene separate during gamete formation so each gamete receives one allele

mendelian phenotypic ratio

the classic phenotypic ratio from a heterozygous monohybrid cross is 3

discrete trait

a trait with distinct categories rather than continuous variation

mendelian trait

a trait primarily controlled by a single gene and inherited according to mendelian principles

mendelian crosses

crosses used to predict inheritance patterns and offspring genotype and phenotype frequencies