Genetics Exam 1 Mizzou Shiu

genetics

genetics

the study of genes, study of heredity, how characteristics are passed from parents to offspring

gene mapping

determining the location of a gene on a chromosome

gene

the basic unit of inheritance (controls one or more characteristic)

alleles

alternative forms of a gene

wild type (WT)

the standard (normal) form usually the most commonly occurring natural variant

mutant

a form different from the wild type

genotype

genetic makeup of an organism. usually only lists the mutant alleles

phenotype

observable properties of an organism (physical)

enzyme

catalyzes biological reactions

prokaryotes

single celled, DNA in cytoplasm and usually one circular DNA

eukaryotes

single or multi celled, DNA in nucleus and has multiple linear DNA in nucleus and one circular DNA in organelles

model organism

organisms that work well for genetic experimentation

saccharomyces cerevisiae

a budding yeast

drosophila melanogaster

fruit fly

caenorhabditis elegans

a nematode

arabidopsis thaliana

thale cress, a member of the mustard family

mus musculus

mouse

homo sapiens

humans

neurospora crassa

orange bread mold

chlamydomonas reinhardtii

a green algae

pisum sativum

a green pea

zea mays

corn

danio rerio

zebrafish

escherichia coli

e coli

transforming principle

what changed dead S and live R into live S strain

Griffith

mouse and streptococcus experiment. proved transforming principle

avery

destroying different components to find transforming principle. proved DNA. wasn’t trusted because of possible contamination

hershey and chase

bacteriophage experiment. put radioactive DNA and proteins into e coli cell and DNA stayed in cell while proteins did not. proved DNA was transforming principle

nucleotide

sugar+base+phosphate

deoxy

without oxygen

deoxyribose

sugar of DNA. has H instead of OH on 2’ carbon

ribose

sugar of RNA. has OH instead of H on 2’ carbon

purines

double rings. nine membered. AG

pyrimidines

one ring, six membered. CUT

nucleoside

sugar+base

polynucleotides

multiple nucleotides bound together by phosphodiester bonds

phosphodiester bonds

the bonds between bases creating the backbone of DNA. asymmetric

double helix

the shape of DNA

Chargaff

proved base pairing. A=T and C=G

Franklin and Wilkins

XRay diffraction showed helical structure. proved lengths between base pairs and one helical turn

.34 nm

length between base pairs

3.4 nm

one helical turn

Watson and Crick

winners of race. 2 polynucleotide chains wound around each other in a right handed helix. antiparallel. sugar on outside bases on inside. base pairing and hydrogen bonds. minor and major grooves

protein coat

surrounding on a viruses nucleic acid

bacteriophages

viruses that infect bacteria

exonuclease

removes nucleotides from the end of linear DNA

plasmid

minor chromosome that is dispensable to the life of the cell. important for DNA cloning

diploid

2

haploid

1

transposable elements

elements that can move positions within the genome

genome

set of information in one complete haploid chromosome set

C value (constant value)

the total amount of DNA in the haploid genome of a species

C value paradox

the structural complexity and the C value of an organism are not related. (human - 3.4 B bp, amoeba - 290 B bp)

chromatin

DNA protein complex that makes up chromosomes

histone

core of chromosome

nucleosome

basic unit of chromatin. histone core + core DNA

euchromatin

usually transcriptionally active (lightly packed) most of the genome

heterochromatin

usually inactive (tightly packed) centromeres and telomeres. repeat sequences at chromosome end

centromeres

where spindles attach

biochemical pathways

multistep process to produce a final product. each step is catalyzed by an enzyme. there are intermediate compounds after each reaction leading to the final product

AKU

urine blackening. first cousin marriages. build up of homogentisic acid in urine. normal people metabolize this acid.

minimal medium

inorganic salts, organic carbon source (sucrose), biotin B7 (vitamin)

prototroph

wild type. a strain that grows on minimal medium

auxotroph

a nutritional mutant that does not grow on minimal medium (requires a supplement

Beadle and Tatum

discovered biochemical pathways through minimal medium + aa experiment. One gene encodes one enzyme

pleiotropic

multiple phenotypic traits from a single mutation

PKU

block of phenylalanine so that it cannot convert to tyrosine. affects CNS, pigmentation, and hormal levels. treatment: supplement tyrosine, limit phenylalanine

essential amino acid

unable to synthesize it, must come from diet

recessive

an allele that is expressed only in the homozygous state

dominant

an allele that is expressed in either the homozygous or heterozygous state

homozygous

an organism with the same alleles for a gene

heterozygous

an organism with different alleles of a gene

albanism

block after tyrosine so that it cannot convert to DOPA which allows melanin. white skin and red eyes. two forms exist allowing for people with albanism to have normal children

Lesch-Nyhan Syndrome (LNS)

HGPRT recycles purines but in LNS pathway is impaired so purines accumulate and turn into uric acid which builds up in tissues causing kidney failure, involuntary spasms, mental deficiency, and self mutilation. X linked so mostly in males

Tay-Sachs Disease (TSD)

HexA cleaves terminal from a brain ganglioside and when ganglioside accumulates it destroys brain and nerve cells. rapid degeneration and usually death by 4

Sickle Cell Anemia (SCA)

RBC change shape under low O2 tension. break easily and block pathways. pleiotropic. non enzymatic. heterozygous less severe and immune to malaria

Cystic Fibrosis (CF)

mutation to channel that allows Cl- into cell. leads to build up of mucus into vital organs. non enzymatic

pedigree

family tree

amniocentesis

a sampling of amniotic fluid (contains fetal shed cells) using a syringe

Chorionic Villus Sampling

sampling of the chorion via the vagina

chorion

a membrane surrounding the fetus

genetic counseling

focuses primarily on informing clients of risks and probabilities of having a child of mutation

transcription

synthesis of an RNA molecule using a DNA template

central dogma of biology

DNA —> RNA—> protein

template strand

noncoding strand. used by RNA pol. read and pairs with mRNA. 3’ to 5’

coding strand

nontemplate strand. same sequence as mRNA. 5’ to 3’

mRNA strand

matches with coding strand and pairs with template strand. synthesized 5’ to 3’

ribonucleoside triphosphates (NTP)

RNA precursors

messenger RNA (mRNA)

encodes the amino acid sequence of a polypeptide

transfer RNA (tRNA)

brings amino acids to ribosomes during translation

ribosomal RNA (rRNA)

forms a ribosome with proteins

ribosome

translation machinery

small nuclear RNA (snRNA)

combines with proteins to form complexes (spliceosomes) used in various processes (intron splicing) only found in eukaryotes

short interfering RNA (siRNA) and microRNA (miRNA)

involved in gene silencing (RNA interference) in some eukaryotes

coding RNAs

translated into proteins (mRNA)

noncoding RNAs

not translated into proteins (everything but mRNA)

promoter sequence

attracts RNA polymerase to begin transcription at a site specified by the promoter in prokaryotes

RNA coding sequence

the transcribed sequence in prokaryotes. includes both translated and untranslated regions

terminator

specifies where transcription stops in prokaryotes

-35 region

promoter in prokaryotes. TTGACAT