Genetics Exam 1

somatic cell

has 23 pairs of chromosomes: 22 autosomes, one pair of sex chromosomes

exome sequencing

determination of order of DNA bases of parts of genome that encode proteins

metagenomics

field involving sequencing of all DNA in a habitat

4 basic tissue types & functions

epithelial: fill spaces throughout body. include cartilage, bone, blood, fat.

connective: tight liners that protect, secrete, absorb, excrete.

muscle, nervous

somatic (body) vs germ (sperm/egg) cells

somatic are diploid, germ are haploid

major macromolecules & their functions

carbs: provide energy, contribute to cell struc.

lipids: basis of some hormones. form membranes, insulate, store energy.

proteins: MANY functions.

nucleic acids: genetic material

rough ER functions

has ribosomes. involved in protein synthesis and folding

smooth ER functions

lipid synthesis

Golgi apparatus functions

adds sugars to form glycoproteins, glycolipids. Good for secretions

Lysosome functions

eat bacterial remnants, worn organelles, and excess cholesterol. Engage in autophagy

endosomes

vesicles from plasma membrane that bring stuff to lysosomes

peroxisomes functions

break down lipids, synthesize bile acids

phospholipids composed of

2 fatty acids (hydrophobic), phosphate (hydrophilic)

cytoskeleton composed of

biggest to smallest: microtubules, intermediate filaments, microfilaments (made of actin)

cell cycle

interphase: G1, S (DNA replicated), G2. Proteins to form mitotic spindle are made, microtubules form centrioles near nucleus

mitosis: PMAT, Cytokinesis

telomeres

at end of chromosomes. lose hundreds-thousands of repeat DNA base sequence; indicate when a cell should stop dividing (track age)

telomerase

prevent shortening of telomeres in sperm, eggs, bone marrow, cancer cells

growth factor

local signal

cyclins and kinases

proteins that interact in cells to activate genes that carry out mitosis

apoptosis

orderly cell death. includes killer enzymes (caspases)

stem cell

produce 2 daughter cells or 1 stem 1 progenitor (latter cannot self-renew)

totipotent

pluripotent

multipotent

toti: give rise to every cell type

pluri: have fewer possible fates

multi: most limited choices

stem cell sources

embryonic stem cell, induced pluripotent stem cell (reprogrammed somatic cell nucleus), 'adult' stem cell (somatic cells that normally func as stem cells)

crossing over vs independent assortment

crossing over happens between homologs in prophase 1.

independent assortment is how hom pairs line up in metaphase 1

functions of

semininferous tubules

epididymis

prostate gland, seminal vesicles, bulbourethral glands

ductus deferens

sem tubules: where sperm cells are made (in testes).

epididymis: where sperm mature and are stored.

prostate, sem vesicles, bulbourethral gland: make seminal fluid.

ductus deferens: transport sperm from epid. to outside.

spermatogonium

diploid cell that makes stem cell and primary spermatocyte

process of spermatogenesis

diploid spermatogonium mitosis -> stem cell + (diploid) primary spermatocyte meiosis I -> 2 (haploid) secondary spermatocytes meiosis II -> 2 (haploid) spermatids --> spermatozoa

process of oogenesis

diploid oogonium -> primary oocyte meiosis I -> small polar body, large secondary oocyte meiosis II -> polar body, mature ovum

oogenesis

oocytes arrest at prophase I til puberty, after which meiosis I continues in some oocytes each month but halts at metaphase II unless fertilized

cleavage

period of frequent cell division of zygote. results in blastomeres (early cells)

morula

embryo: solid ball of 16+ cells

blastocyst

morula hollows out and center fills with fluid

inner cell mass

some blastocyst cells form clump on inside lining. it develops into embryo

trophoblast

outermost blastocyst cells that secrete hormone hCG that prevents menstruation

primary germ layers

form in 2nd week post-fertilization. three-layered struc = gastrula.

ectoderm (outermost)

meosderm (middle)

endoderm (innermost)

organogenesis

transformation of 3 simple germ layers into distinct organs

law of segregation

states elements separate in gametes

test-cross

test where you cross individual of unknown genotype with individual of homozygous recessive genes

dihybrid

RrYy

parental chromosomes

have OG configuration

recombinant chromosomes

have new allele combos

epistasis

when one gene affects expression of a second gene

penetrance

all-or-nothing expression of a single gene (completely penetrant = all individuals express phenotype)

expressivity

severity or extent of gene expression

pleiotropy

when one gene controls several functions or has more than one effect

epistasis

one gene masks or otherwise affects another's phenotype

phenocopy

environmentally caused condition has symptoms and recurrence pattern similar to those of known inherited trait

genetic heterogeneity

genotypes of diff genes cause same phenotype

heteroplasmy

when mtDNA sequence isn't same in all copies of genome. during mitosis, mitochondria distributed at random into daughter cells

linkage disequilibrium (LD)

nonrandom association between DNA sequences

haplotypes

LD blocks used to track genes in populations

LOD (logarithm of odds) score

indicates tightness of linkage between marker and gene of interest

sex-limited traits

affect a structure or function present in only one sex (beard growth, mlik production, preeclampsia)

sex-influenced traits

allele dominant in one sex but recessive in the other (pattern baldness)

Barr body

dark-staining X chromosome that's been deactivated in females (during interphase only)

manifesting heterozygote

female expressing phenotype of x-linked gene

genomic imprinting

methyl groups bind to gene(s) to prevent expression. 'imprinted gene' is deactivated.

erased during meiosis then reassigned based on individual sex.

reproductive ducts

Mullerian (female specific) and Wolffian (male specific)

sex ratios

calculated by # males / #females x 1000.

primary sex ratio: at conception

secondary: at birth

tertiary: at maturity

empiric risk

probability that a trait will recur based upon its incidence in a population

heritability (H)

Proportion of phenotypic variation due to genetics. (heritability = 1.0 means variability is completely result of gene action)

quantitative trait loci (QTLs)

DNA sequences involved in polygenic traits

genome-wide association study (GWAS)

compares many genetic markers across the genome between two large groups of people: one w disease, one without

single nucleotide polymorphism (SNP)

used in GWAS. Sites in genome that has diff DNA base in >1% of a population.

copy number variants (CNV)

DNA sequence that repeats diff num of times in diff individuals (good for forensics)

cohort

follow many people over time and measure several traits

case-control

people in 2 groups individually matched for several characteristics. differences in SNP identified

affected sibling pair

identify SNPs that siblings with same condition share, but siblings who don't both have condition don't share

homozygosity mapping

disease-causing mutations identified in homozygous genome regions that children inherit from parents who are related to each other

leptin

produced by fat cells that decreases appetite

ghrelin

produced in stomach that signals hunger and increases appetite (stimulate neuropeptide Y)

cataplexy

period of muscle weakness

how autism develops

neurexins (presynaptic neurons) and neuroligins (postsynaptic neurons) misfold so they can't interact and pull neurons closer for connection

Miescher

isolated nuclei from WBC; found nuclein

Griffith

termed conversion of one bac type to another as 'transformation'

Avery, MacLeod, McCarty

discovered DNA (not protein) caused transformation of bac types, so DNA is 'transforming principle'

Hershey + Chase

showed virus transfers DNA (not protein), so DNA is genetic material

Levene

found RNA ribose, DNA deoxyribose. Discovered 3 parts of nucleotide

Chargaff

found AG, TC relationships

Franklin, Wilkins

found 2 forms of DNA

Watson + Crick

used cardboard models to solve DNA struc

histones

proteins that DNA coils around

nucleosome

bead-like structure (where DNA wraps around histone)

helicase

unwinds DNA helix

binding proteins

stabilize separate strands of DNA

primase

adds short RNA primer to template strand

DNA polymerase

binds nucleotides to form new strands that are added to RNA primer.

also proofreads

ligase

joins Okazaki fragments, seals other nicks in sugar-phosphate backbone

Sanger sequencing

Dideoxynucleotides halt DNA polymerization at each base, generating sequences of various lengths that encompass the entire original sequence. Terminated fragments are electrophoresed and the original sequence can be deduced.

Next-generation sequencing

uses massively-parallel approach and immobilizes DNA pieces on diff types of materials to spead up DNA sequencing

rRNA

associated w certain proteins to form ribosomes

RNA processing includes...

adding meth cap to 5' end (recognition site for protein synth), adding poly A tail to 3' end (protein synth beginning; stabilizes mRNA), splicing (remove introns), proofreading

alternative splicing

combine exons of genes in diff ways to make diff version of a protein called isoforms

open reading frame

reading frame with no stop codon

ribozymes

rRNA that functions as catalysts

transcription factors

interact to form apparatus that binds DNA at certain sequences to initiate transcription at specific sites.

respond to outside cell signals.

link genome to environment.

synonymous codons

diff codons that code for same amino acid

chaperone proteins

stabilize partly folded protein regions, prevent protein from getting stuck in intermediate form. used in drugs to help w diseases

dealing w misfolded proteins

tag em with ubiquitin. proteasomes see proteins w >1 tag and straightens them and breaks em down

prion protein

misfolded protein that can aggregate and clump, and cause other proteins to misfold