genetics DNA & chromosomes test

gene

a sequence of DNA that tells a cell how to assemble amino acids into a particular protein

Fredrich Miescher

isolated nuclein in white blood cell nuclei

Fredrick Griffith

Transferred killing ability between types of bacteria

Oswald Avery, Colin MacLeod, Maclyn McCarthy

Discovered that DNA transmits killing ability in bacteria

Alfred Hersey, Martha Chase

determined that the part of a virus that infects & replicates is its nucleic acid & not its protein

Phoebus Levene, Erwin Chargaff, Maurice Wilkins, & Rosalind Franklin

discovered DNA components, proportions, & positions

James Watson & Francis Crick

explain DNA's three-dimensional structure

James Watson

Had his genome sequenced

Protein

imparts phenotypes

nucleotide

- deoxyribose sugar
- phosphate group
- nitrogen base

A & G purines

2 ring structure

T & C pyrimidines

single ring structure

DNA structure has a sugar-phosphate back bone with

nitrogen bases in between

in a DNA structure, 2 chains of nucleotides align

head to toe

antiparallel

5' to 3'; direction in which complement strand grows

DNA structure forms a

double helix

base pairs are held together with hydrogen bonds

A & T: 2 H+ bonds
G & C: 3 H+ bonds

DNA structure twists to fit in

the nucleus

histones

proteins that DNA wraps around

nucleosome

DNA wrap around 8 histones

linker region

strand of DNA that tighten nucleosome together

linker regions help to

open parts of DNA at a time for protein synthesis

Chromatin

DNA, histones, DNA scaffold, & proteins to bind DNA & RNA

Chromatid

unreplicated chromosome

chromosome

made up of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes

DNA unwinds, separates, exposing

unpaired bases that attract free floating nucleotides

new double helix has _ of original DNA

1/2

Matthew Meselson & Franklin Stahl

Showed that DNA replication is semi-conservative

steps of DNA replication occurs in phase _ of cell cycle

s

steps of DNA replication

1. replication fork
2. helicase
3. primase
4. DNA polymerase

replication fork

site where DNA locally opens to pair up

helicase

enzyme that breaks H+ bonds between base pairs

primase

attracts complementary RNA nucleotides to build a short piece of RNA primer at the beginning of DNA

DNA polymerase

main replication enzyme that
1. removes RNA primer once the strand is started
2. replaces with correct DNA nucleotides
3. nucleotides come from nutrients in our diet

why do we need RNA in DNA replication?

DNA polymerase needs a started strand to add nucleotides

ligase

enzyme that seals the sugar-phosphate backbones

Okazaki fragments

about 150 nucleotides long on discontinuous piece of DNA

helicase at the replication fork

helps to open the DNA to identify where DNA replication should start

leading & lagging strands

leading: continuous
lagging: discontinuous (goes & stops; fragments)

Polymer

A long molecule consisting of many similar or identical monomers linked together.

DNA replication is conducted

outside cells

DNA amplification uses DNA polymerase to

replicate a specific DNA sequence in a test tube

polymerase chain reaction (PCR) requirements

1. 2 primers
2. complements to target sequence
3. many copies of 4 types of DNA nucleotides

why is it necessary for the DNA polymerase to be from a bacteria that lives in hot springs?

to withstand heat to force DNA replication

PCR steps

1. Denaturation
2. Annealing
3. Extension

Denaturation

loss of normal shape of a protein due to heat or other factor

Annealing

Binding of primers

Extension (PCR)

produces new DNA fragments in which the reaction mixture is heated to the optimal temperature for DNA polymerase, and each primer is elongated by means of deoxynucleotide triphosphates

PCR results

- identical DNA pieces accumulate at a rate of 2^n
- after 30 cycles of PCR yields more than 10 billion copies of target DNA sequence

n = number of

temperature cycles

why is it important to have so much replicated DNA?

cells must replicate their DNA before they can divide. this ensures each daughter cell gets a copy of the genome & therefore successful in inheritance of genetic traits

Fredrick Sanger

Determined amino acid sequence of proteins.

sanger sequencing generates

a series of DNA fragments of identical sequence that are complementary to the DNA sequence of interest; fragments differ in length by 1 end base

one technology other than PCR that uses Sanger sequencing

CRISPR genome editing technique in complex organisms

chain termination

the release of a newly formed protein from the ribosome; also halts DNA replication

if a DNA molecule contains 20% adenine, what percentage of guanine is present?

30% - because in total they have to equal 100

the 2 strands in a DNA molecule are

antiparallel and complementary

purines are bases with a two-ring structure

adenine & guanine

labels of 5' & 3' refer to

numbered carbons on the sugar

the method of DNA replication is now known to be

semiconservative

the enzyme that attracts complementary RNA nucleotides to build an RNA primer at the start of replication

primase

the enzyme that serves to seal the sugar-phosphate backbone after replication

ligase

replication proceeds in a

5' to 3' direction

okazaki fragments form on the

lagging strand

if the sequence of one strand of DNA is 5' ATGGCAT 3', the sequence of the complementary strand is

3' TACCGTA 5'

DNA in the nucleus winds around proteins called

histones

antiparallelism means

the 2 strands of a DNA molecule run in opposite directions

in DNA replication,

the parental DNA splits & free nucleotides bond to their complements, building 2 DNA molecules from 1

because DNA strands are antiparallel, replication proceeds

continuously on one strand, & discontinuously on the other

Helicase

An enzyme that untwists the double helix of DNA at the replication forks (unzipper)

leading strand

The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.

lagging strand

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 3' to 5' direction away from the replication fork.

Primase

An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.

RNA nucleotides

adenine, cytosine, guanine, uracil

DNA structure

- double-stranded
- thymine as base
- deoxyribose as sugar

RNA structure

- single-stranded
- uracil as base
- ribose as sugar

3 types of RNA

messenger, transfer, ribosomal

transcription

takes a copy of the dna out to the ribosome to make a protein

translation

making protein from RNA

Archibald Garrod

first to link inherited disease between protein & genetic material

Pheobus Levene

discovered structure of DNA & found difference between DNA & RNA

Erwin Chargaff

discovered that A=T and G=C

backbone of DNA structure

sugar and phosphate

DNA structure ladder

nitrogen bases (A-T; G-C)

semiconservative

DNA structure

how does DNA fit into the nucleus?

it twists

bonds involved in DNA

Hydrogen bonds that hold nitrogen bases together

A & T have how many nitrogen bonds?

2

G & C have how many nitrogen bonds

3

Chargaff's rule

Equal number of adenine and thymine and equal number of guanine and cytosine

pyrimidines

thymine & cytosine; single-ring structure

purines

adenine & guanine; double-ringed structure

what to pyrimidines & purines do together?

they bond together which is why the double helix has the same width

deoxyribose carbon structure

the phosphate group attaches to the 5' carbon on the sugar; 5' carbon attaches to the sugar

what does the deoxyribose sugar contain?

5 carbon
4 oxygen
10 hydrogen

semiconservative model

means the newly replicated strand of DNA is made up of one original strand & one new strand

complementary strands

DNA is made up of 2 complementary strands

difference between introns & exons

introns don't code for proteins while exons do

nucleotide structure parts

nitrogen group, sugar, phosphate

what enzymes are involved in DNA replication?

DNA polymerase, primase, ligase, helicase