1406 Exam 5

Gregor Mendel

Father of genetics, studies inheritance

Genes

DNA segments that serve as the key functional units in hereditary transmission. Called heredity factors by Mendel

Phenotype

An organism's physical appearance, or visible traits.

Genotype

An organism's genetic makeup, or allele combinations. AA, Aa

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape. Looking for chromosomal abnormalities.

Pedigree

A chart or "family tree" that tracks which members of a family have a particular trait. If every generation shows trait, suggests that trait is dominant

Homozygous

An organism that has two identical alleles for a trait AA or aa

Heterozygous

An organism that has two different alleles for a trait Aa

Phenotype ratios when crossing homozygous dominate to recessive and then into the F2 generation. AA x aa

3 dominant : 1 recessive

Phenotypic ratio for dihybrid if both parents are heterozygous for both traits. AaBb x AaBb

9:3:3:1

ABO blood groups

Genetically determined by multiple alleles

polygenic traits

traits controlled by two or more genes, human height

incomplete dominance

Situation in which one allele is not completely dominant over another allele, see blending of traits. Red (RR) x white(WW) makes pink (RW)

dominant disorders

Achondroplasia, Huntington's disease

sex-linked traits

Traits controlled by genes located on X chromosome. Colorblindness & hemophilia are recessive

genetic map

distances between gene loci along a particular chromosome, determined by recombination frequency

independent assortment

Independent segregation of genes during the formation of gametes, will occur if allele pairs are on different chromosomes

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Pleiotropy

The ability of a single gene to have multiple effects. Cystic fibrosis & sickle cell anemia

Nondisjunction

Error in meiosis in which chromosomes or chromatids fail to separate. Unequal number of chromosomes in gametes

Turner Syndrome

A chromosomal disorder in females in which either an X chromosome is missing, making the person XO instead of XX, or part of one X chromosome is deleted.

Klinefelter syndrome

A chromosomal disorder in which males have an extra X chromosome, making them XXY instead of XY.

Jacob's Syndrome

XYY males

SRY gene

sex determining region of the Y chromosome, if mutated/deleted then develop as female

Relationship between recombination frequency and physical distance on a chromosome

As distance increases, recombination frequency will reach and level off at .5

Mitochondrial DNA

DNA found in the mitochondria that is inherited only through mothers

SNPs

are single base differences in DNA that vary among individuals, can be used in forensics

Central Dogma

DNA -> RNA -> Protein

protein synthesis phases

transcription and translation

mRNA (messenger RNA)

The form of RNA which is created as a blueprint from DNA; carries instructions for making a protein

tRNA (transfer RNA)

The form of RNA that carries each amino acid to the ribosome to form the polypeptide chain (protein)

rRNA (ribosomal RNA)

type of RNA that makes up the major part of ribosomes

snRNA

small nuclear RNA, used to remove introns

miRNA

micro RNA, regulates gene expression, binds directly to mRNA to form double stranded RNA which prevents translation

Transcription

synthesis of an mRNA molecule from a DNA template, occurs in the nucleus for eukaryotes, RNA polymerase must have access to DNA and bind to promoter

Translation

Process by which mRNA is decoded and a protein is produced, occurs in the cytoplasm

Splicing

the process of removing introns and reconnecting exons in a mRNA

Codon

three-base sequence on messenger RNA that codes for a single amino acid, AUG

Anti-codon

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

peptide bond

covalent bond formed between amino acids to form proteins

phosphodiester bond

the type of bond that links the nucleotides in DNA or RNA.

hydrogen bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom.

Prokaryotic Protein Synthesis

Translation of mRNA begins before transcription is complete. No introns and exons

Eukaryotic Protein Synthesis

DNA in nucleus, linear chromosomes, DNA wound on histone proteins, mRNA is modified, introns and exons, transcription and translation happen separately

mRNA modifications in eukaryotes

3' poly A tail, 5' cap and removal of introns

transcription initiation complex

The completed assembly of transcription factors at TATA box and RNA polymerase bound to a promoter.

substitution mutation

A mutation in which 1 base or a codon in DNA is replaced with a different base, protein may not function properly

silent mutation

A mutation that changes a single nucleotide, but does NOT change the amino acid created.

nonsense mutation

changes a normal codon into a stop codon, results in a shorter than normal protein

Deletion or insertion mutation

The production of entirely different or nonfunctional protein due to frame shift

Major groove of DNA

main site of protein binding to regulate gene expression

operon organization

regulatory genes, promotor, operator, genes

(upstream) (downstream)

Nucleosome

Bead-like structure in eukaryotic chromatin, composed of a short length of DNA wrapped around a core of histone proteins

Histones

protein molecules around which DNA is tightly coiled

lac operon

the operon that controls the metabolism of lactose

lac repressor

a protein that binds to the operator site of the lac operon and inhibits transcription, if mutated then energy and materials wasted if no lactose present

operon

A unit of genetic function common in bacteria (prokaryotes), consisting of regulated genes with related functions.

promoter region of DNA

where RNA polymerase attaches and where initiation of mRNA begins

Enhancers

A segment of eukaryotic DNA containing multiple control elements, usually located upstream from the gene whose transcription it regulates.

methylated histones

DNA is not transcribed, inactive chromatin

translation repressor proteins

proteins that prevents translation of mRNA by binding to the mRNA and preventing ribosome attachment

ubiquitinated proteins

are degraded by proteasomes

Nucleases

Enzymes that break down nucleic acids such as mRNA by 5' decapping, remove poly A tail and degrade recognition sites

one gene-one protein hypothesis

there is one gene that codes for one protein, not true due to alternative splicing so produce different proteins in different tissues

trp operon

tryptophan binds to the repressor protein and enables it to repress gene transcription.