genetics final review

transmission genetics

passing of traits from parents to offspring

molecular genetics

DNA leading to RNA leading to protein

population genetics

studying traits in an entire population

model organism

1. organisms with characteristics that make them useful for genetic analysis. If you want a model organism similar to humans, you have to go up in complexity like mice

• short generation time

• production of numerous progeny

• ability to be raised in a lab

gregor mendel

• father of genetics

  • principles of heredity

  • 1850s, same time as Darwin

schleiden and schwann

• came up with cell theory

• viruses are not living organisms

• disproved that life could spring out of nothing

cell theory

all organisms are made of cells and all cells come from pre-existing cells

darwin

• discovered evolution and natural selection

natural selection

varying traits and fitness. some traits are more favorable than others

sutton

• discovered that genes are located on chromosomes

watson and crick

structure of DNA

roselyn franklin

used x-ray crystallography to help watson and crick

hershey and chase

DNA is the genetic material

bacteriaphage in blenders

messholson and stall

figured out how DNA replication works

semiconservative replication

genome

complete set of genetic instruction for an organism

only viruses have RNA for a genome

gene

section of DNA that encodes a protein

central dogma of molecular biology

DNA is the genetic material, then it’s transcribed to make RNA template, then RNA leaves nucleus where it is translated into a protein

• replication - in the nucleus

• transcription - makes RNA copy of DNA. moves to the ribosomes

• translation - proteins are made in the ribosomes

4 features of genetic material

• complex information

• accurate replication

• ability to vary/ mutations

• encode a phenotype

Griffith

• pneumonia in mice, rough strain and smooth strain

• discovered transformation

avery, mccleod, mccarty

• DNase

• Protease

• RNase

• R and s strain

• DNA is the genetic material

Hershey and Chase

bacteriaphage in blenders

DNA is the genetic material

Chargroff

• complimentary base pairing

• A=T and C=G

• number of purines = number of pyrimidines

nucleotide

• made of sugar, phosphate group, nitrogenous base

• ATCG

purines

• adenine and guanine

• 2 ring structures

pyrimidines

• cytosine and thymine

• single ring structures

DNA structure

• backbone made of sugars linked by phosphates

• double stranded antiparallel

• sugar: deoxyribose

RNA structure

• single stranded

• sugar: ribose

phosphodiester bond

bonds that form the sugar and phosphate backbone of DNA

hydrogen bond

holds the 2 strands of DNA together

• T + A = 2 hydrogen bonds

• C + G = 3 hydrogen bonds

B form

• most common form of DNA found in cells

• right handed helix

• follows Watson and Crick model

A form

• found in dehydrated cells

• right handed helix

• twisted more tightly than B form

Z form

• not really certain this exists irl

• left handed helix

• exists because scientists manipulated it

bacterial DNA

• single circular chromosome

• more euchromatin than humans but less heterochromatin

euchromatin

• many genes

• chromatin is less condensed

• transcription is often

heterochromatin

• very few genes

• chromatin is more condensed

• transcription is infrequent

• junk DNA - non-coding B form

nucleosome

DNA wrapped around histones

chromatin

the form of DNA in interphase of the cell cycle

looser form

chromosomes

DNA and proteins more compact during mitosis

tightest form of DNA

conservative model of replication

results in one original DNA molecule and one all new DNA molecule

dispersive model of replication

part new and part old alternating like a puzzle

like a hybrid

semiconservative model of replication

one strand of original DNA and one strand of new DNA twisted

replication origin

where replication begins

theta replication

circular replication

helicase

unzips the DNA and breaks the hydrogen bonds

gyrase

puts nicks in the sugar phosphate backbone to prevent supercoiling

primase

adds a short primer so DNA POL III can attach

DNA POL III

attaches to primer during replication to add bases

only works 5’ to 3’

single stranded binding proteins

keeps the helix open

prevents hydrogen bonds from forming back together

DNA POL I

removes the RNA primers and adds appropriate DNA bases

ligase

seals the gap where the primer was

proof reading

DNA POL can back up one base to fix a mistake

during replication

mismatch repair

DNA POL corrects the errors after replication is complete

telomere

the ends of our linear chromosomes

telomerase

adds junk DNA to the end of chromosomes so when telomeres are shortened after rounds of replication, only not important DNA is lost

primary RNA structure

single stranded RNA

ACGU

secondary RNA structure

RNA folds in on itself

EX: cloverleaf, hairpin

internal base pairing

when RNA folds in on itself, hydrogen bonds between bases form

rRNA

• ribosomal RNA

• physical part of the ribosome

mRNA

• messenger RNA

• carries information for a gene, used to form a protein

tRNA

• transfer RNA

• brings amino acids to the ribosomes

snRNA

small nuclear RNA

splices pre- mRNA

SnRNP

used for RNA processing

cut out the intons and fuse the exons

siRNA

small interfering RNA

gene expression

if protein is not needed but DNA is already transcribed, this degrades the mRNA to prevent translation

promoter

a specific DNA sequence that tells RNA POL where to start. RNA POL binds here to open up the double helix. sigma factor binds here as well

RNA coding sequence

RNA POL adds on the complimentary bases for RNA

terminator

transcription ends here

RNA POL

builds the RNA 5’ to 3’

sigma factor

binds to the promoter when transcription starts

Rho

protein that attaches to mRNA during transcription once RNA POL gets to the terminator.

uses helicase to separate mRNA from DNA template

5’ cap

pre mRNA modification

backwards guanine directs mRNA to the ribosomes

poly A tail

pre mRNA modification

many adenines added on the end of RNA to prevent degradation in the cytoplasm

splicing

post mRNA modification

introns are removed and exons are fused together

exon

expressed sequences

intron

intervening sequence

amino acid

essential carbon bound with an amino group, carboxyl group, hydrogen, and R group

R group is what differs between amino acids

peptide bond

bond between 2 amino acids

codon

3 sequential bases that will translate into one amino acid

sense codon

encode for any amino acid

start codon

codon that codes for MET

termination codon

say stop coding

reading frame

part of the genetic sequence that’s encoding for RNA or making proteins

wobble hypothesis

• james watson

• It states that the third base of a codon (in mRNA) can sometimes pair with multiple bases in the first position of the anticodon (in tRNA)

tRNA charging

attaches the amino acid to the correct tRNA

aminoacyl tRNA synthase

enzyme responsible for tRNA charging

initiation of translation

• in cytoplasm

• ribosome breaks into small and large subunit

• mRNA joins to the small subunit

• tRNA attaches to start codon

• large subunit smooshes everything together

elongation of translation

• everything slides down one codon at a time to grow the polypeptide

  • A - aminoacyl site - tRNA arrives here

  • P - peptidyl site - peptide bond forms between MET and incoming amino acid.

  • E - exit site - tRNA leaves charged with MET

termination of translation

termination codons are read

release factors enter A site and everything comes apart

diploid

chromosomes come in pairs

2n=46

haploid

one of each chromosome

gametes

1n=23

allele

different forms of a gene

sister chromatid

when a single chromosome replicates and joins to its replicate, the two chromosomes are sister chromatids

identical

G1

• part of interphase

• cellular function, metabolism, actively dividing

G0

offshoot of G1

cell is not actively dividing

S stage

section of interphase

DNA is replicating

G2

section of interphase

cell prepares for division

G1 checkpoint

makes sure the DNA is healthy before it starts duplicating

kinases

• enzymes that pause the cell cycle

• mutations in kinases lead to cancer

G2 checkpoint

cell cycle checkpoint that ensures DNA replicated properly

spindle assembly checkpoint

during mitosis, ensures spindle fibers attach to centromeres properly

genotype

set of alleles possessed by an individual organism