BIO 101 Chapter 11, 12, 13

allele

An alternative form of a gene.

anticodon

group of three bases on a tRNA molecule that are complementary to an mRNA codon

antiparallel

referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5' -3' directions).

autosomal dominant genetic disorders

individuals that are homozygous dominant or heterozygous will have the disorder; homozygous recessive individuals do not have the disorder

autosomal recessive disorders

homozygous dominant genotypes do not have the disorder; heterozygous genotypes are carriers; homozygous recessive genotypes do have the disorder

Carcinogen

substance that causes cancer

carrier

an organism that heterozygous for a recessive genetic disorder; the individual is unaffected by can pass the disorder on to offspring

Central Dogma of Molecular Biology

DNA --> RNA --> Protein --> Observed Trait

Chargaff

Analyzed DNA from many species. Found that [A=T] and [G=C]

codominance

A condition in which neither of two alleles of a gene is dominant or recessive; the heterozygous genotype results in both of the phenotypes being expressed; example - roan horse

codon

A specific sequence of three adjacent bases on a strand of mRNA that provides genetic code information for a particular amino acid

color blindness

an X-linked recessive disorder that affects color vision

dihybrid cross

Cross or mating between organisms involving two pairs of contrasting traits

DNA

deoxyribonucleic acid; double stranded; has thymine

DNA helicase

unwinds DNA

DNA ligase

an enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments

DNA polymerase

synthesizes new DNA by adding DNA nucleotides to a growing strand

DNA replication

the process of making a copy of DNA

dominant allele

allele that is always expressed if present; it can mask or cover up the recessive allele

epistasis

one gene interferes with the expression of another gene; example - coat color in labs

F1 generation

the first generation of offspring obtained from an experimental cross of two organisms

F2 generation

offspring of the F1 generation

frameshift mutation

the insertion or deletion of a nucleotide in the DNA gene sequence that alters all of the codons "downstream" of the mutation

gene

segment of DNA that codes of a functional product (usually a protein) and therefore controls a trait

genetic disorder

medical conditions caused by alleles inherited from parents; can be autosomal or sex linked, dominant or recessive

genetics

The scientific study of heredity

genotype

actual alleles for a gene

hemophilia

an X-linked recessive disorder that resulting in failure of blood to clot

heterozygous

when an organism possess two different alleles for a gene

homozygous

when an organism possess two identical alleles for a gene

hydrogen bonds

hold complementary nitrogenous bases together in DNA

incomplete dominance

A pattern of inheritance in which two alleles are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits; example- four o'clock flowers

induced mutations

result from environmental exposure to mutagens

James Watson and Francis Crick

The scientists credited with building the first correct model of the structure of DNA

law of independent assortment

the law that states that genes separate independently of one another in meiosis

law of segregation

Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

Mendel

Father of Genetics; responsible of the Law of Inheritance and Law of Independent Assortment

monohybrid cross

A cross between individuals that involves one pair of contrasting traits

Monomer of nucleic acids

nucleotides

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

multiple alleles

three or more forms of a gene that code for a single trait; example - multiple alleles

mutagen

A chemical or physical agent that interacts with DNA and causes a mutation.

mutation

change in the nucleotide sequence of DNA

noncoding strand

side of the DNA that is not copied

Nucleotide

consists of a five-carbon sugar, a phosphate group, and a nitrogenous base

P generation

Parental generation, the first two individuals that mate in a genetic cross

Particulate Theory of Inheritance

a theory proposed by Mendel that states that traits are inherited as discrete units that remain unchanged as they are passed from parent to offspring and are just reshuffled from one generation to the next

pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

phenotype

physical manifestation of the genotype

pleiotropy

single gene affects two or more distinct and seemingly unrelated traits

point mutation

a change in a single nucleotide pair of a gene

polygenic inheritance

single trait is governed by more than one gene; example - human height and skin color

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Purines

have double carbon rings, like adenine and guanine

Pyrimidines

have single carbon rings, like cytosine and thymine

recessive allele

only expressed in the homozygous condition

ribosome

made of rRNA and proteins

RNA

ribonucleic acid; single stranded; has uracil instead of thymine

RNA polymerase

enzyme that connects loose RNA nucleotides together according to complementary base pairing for the template strand

Rosalind Franklin

Used X-ray diffraction to discover the double-helical structure of DNA.

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

semiconservative

method of replication that implies that each new strand of DNA is half original and half new

spontaneous mutations

random change in the DNA due to errors in replication or cell division

start codon

codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein

stop codon

codon that signals to ribosomes to stop translation

template strand

side of the DNA that is copied into mRNA

test cross

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

X-linked genes

Genes found on the X chromosome that do not code for gender