slide 9 pt 1

what is genetics?

the study of heredity

what are 4 things included in the study of heredity

1. Transfer of traits from parents to offspring

2. Expression and variation of those traits

3. Structure and function of genetic material (RNA, DNA)

4. How genetic material changes or evolves

the genome is __ of the genetic material housed in a cell

ALL

what does the genome consist of

Chromosome

• Plasmids (Bacteria and Fungi)

• Mitrochondrial (Eukaryotes)

• Chloroplast (Photosynthetic Eukaryotes)

the genome is made of , but what is the exception?

DNA , viruses

chromosomes are a cellular structure made of

packaged DNA

where are Eukaryotic Chromosomes located

in the nucleus

Eukaryotic Chromosomes shape

linear

Eukaryotic Chromosomes packaging

DNA is wound around histone proteins

Eukaryotic Chromosomes number

cells usually have variable numbers of chromosomes

Prokaryotic Chromosomes packaging

no histones

Prokaryotic Chromosomes location

no nucleus

Prokaryotic Chromosomes shape

circular

Prokaryotic Chromosomes number of chromosomes

1 single chromome

gene is the fundamental unit of —

heredity

genes are part of a chromome that causes

some cell function

gene is a length of DNA that contains the information necessary to

make a protein or RNA molecuels

what are the 3 categories that describe the job that a specific length of DNA is designed to do

Structural genes: Encode proteins

2. Genes that encode RNA

3. Regulatory genes: Genes that control gene expression

Supercoiling occurs when the —

DNA double helix is twisted even further upon itself.

A superhelix is simply the — formed by a—. When the DNA axis itself crosses over itself, it creates a—

geometric shape, supercoiled molecule, secondary helix—a helix made of a helix.

Genomes have to be compacted to fit inside —

the cell

E. coli genome how many chromosomes

Single chromosome

E. coli how many genes

4,288 genes

E. coli genome length

Length of 1 mm (1000x longer than the

cell!)

Humans genome how many chromosomes

46 chromosomes

humans how many genes

31,000 genes

humans genome length

Length of 6 feet (180000x longer than the

cell!)

DNA is Made of strands of —

nucleotides

what are the nucleotides that make up DNA

Phosphate

• Deoxyribose sugar

• Nitrogen base

2 examples of nitrogen bases

Purines and Pyrimidines

Purines are made of

Adenine (A) and Guanine

(G)

Pyrimidines- are made of

Thymine (T) and

Cytosine (C)

what the DNA Structure arrangement

Antiparallel arrangement

explain the actual Antiparallel arrangement

5’ to 3’ (prime) or 3’ to 5’

Nucleic Acids are the Building blocks of —

DNA

Nucleic Acids Components

Phosphate Group

• Nitrogenous Base

• Five Carbon Sugar

Phosphodiester bonds-

explain

covalent bonds that link

phosphate group attached

to the 5’ carbon of one

nucleotide to the hydroxyl

group attached to the 3’

carbon of the next

DNA Replication is

Duplication of the chromosome

DNA Replication steps summary

Chromosome uncoils

2. The hydrogen bonds holding the double helix together “unzip”

3. Two new strands are made, using the original strands as templates

what is Origin of replication:

The site where DNA replication starts

Origin of replication is a Segment of —-

DNA that has lots of As and Ts

Why would the origin of replication section be a good site for DNA replication to start?

Fewer H-bonds, easier to split the helix

how many steps in dna replication?

5

DNA gyrase function

relieves supercoiling

tension in front of the replication fork

as the helix opens (negative

supercoils)

Helicase function

breaks H bonds between

nitrogenous base pairs- separates

the DNA strands

A bacterial chromosome will have two

—

replication forks

replication forks are where

Where new DNA is being synthesized

DNA Polymerase III The enzyme that

—

synthesizes replicating DNA

DNA Polymerase III Must have an — to

start

RNA primer

DNA Polymerase III can only read tempate in what direction, what does it mean in makin?

Can only read the template

strand in the 3 ’→ 5’ direction

• Which means it can only make

DNA in the 5’ → 3’ direction

DNA Polymerase III is the — strand

Leading strand

explain this and explain what the yellow and purple are

Step 1: Unzipping the double helix

• Enzymes first must make supercoiled

DNA accessible

DNA gyrase relieves supercoiling

tension in front of the replication fork

as the helix opens (negative

supercoils) (YELLOW)

Helicase breaks H bonds between

nitrogenous base pairs- separates

the DNA strands (PURPLE)

explain and what is red and green

Step 2: RNA Primers

DNA Polymerase III (we’ll come back to this

enzyme) can’t make DNA without a

nucleotide “guide” (RED)

• A short sequence of RNA, called an RNA

primer, is made at the origin of replication by

a primase enzyme to start the replication

process (GREEN)

explain and what is the red

Step 3: DNA Polymerase III

DNA Pol III: The enzyme that

synthesizes replicating DNA

• Must have an RNA primer to

start

• Can only read the template

strand in the 3 ’→ 5’ direction

• Which means it can only make

DNA in the 5’ → 3’ direction

this is the Leading strand

explain

Step 3: DNA Pol III

• Lagging strand synthesis

• Each fragment requires a new

primer

• DNA Pol III works backwards on

this strand, still making the new

DNA in the 5’ → 3’ direction

• The short DNA fragments are

called Okazaki fragments

explain

Step 4: DNA Pol I

• DNA Polymerase I

• Removes the RNA primers from

the Okazaki fragments

• The gaps between fragments are

filled in

explain

Step 5: Ligase

• Ligase

• Connects the phosphate

sugar backbone

segments of fragments

on the lagging strand

A bacterial chromosome will have two

—

replication forks

replication forks is where

• Where new DNA is being synthesized

What happens when we hit the end? of DNA Replication

They reach a termination site and replication shuts down

• A helicase cuts (nicks) the still-connected strands

• They become two daughter chromosomes

Rate of Replication

• Has to be —

• ~— bases per second in bacteria

fast!, 750

DNA Encodes three things:

Proteins

• RNA

• Expression regulators

Codons- definiton

groups of three base

pairs that encode an amino acid

DNA is transcribed into —

—

messenger RNA (mRNA

How does RNA differ from DNA?

• —

Single stranded

• Uracil replaces Thymine

• Different sugar (ribose instead of deoxyribose)

Several different forms of — exist

• Only — becomes protein

RNA, mRNA

Transcription does what

Making mRNA

Transcription Three steps:

1. Initiation

2. Elongation

3. Termination

• The enzyme responsible for transcription

RNA Polymerase

Step 1: Initiation

RNA Pol has to recognize a specific spot on a gene that needs to be

transcribed into mRNA

Promoter region: definition

two sets of DNA sequences that guide RNA Pol to the

start site

Sigma factor definition

: Special protein that helps RNA Pol find the promoter

Step 2: Initiation

RNA Pol unzips the DNA helix and forms a bubble where

transcription can occur

in Step 2: Initiation Only one strand of DNA is transcribed:

template strand, 3’ to 5’ strand is the template strand

start codon: TAC (AUG on the template strand) is where

—

translation starts on mRNA

what happens in Elongation

The mRNA molecule is synthesized, mRNA molecule is 5’ to 3’, DNA is “re-zipped” after transcription occurs

Termination what happens

RNA Pol hits a site on the DNA that signals termination

• The complete mRNA is separated and released from the

transcription machinery

How long is mRNA?

• Varies

• Can be as short as 100 nucleotides

• Average: 600 nucleotides

• Up to 1500 nucleotides!

dna -rna - amino acid genetic code what is it

A, T, G, C → U, A, C, G → Amino

Acids

what is Messenger RNA (mRNA) sequence

5’-AUGUUCGCUAGUUAA-3’

Translation steps

1. Initiation

2. Elongation

3. Termination

4. Protein Folding

5. Processing

Translation Step 1: what happens and what 2 players are therer

mRNA leaves the

transcription site and

moves to the ribosomes

mRNA binds the small

subunit of the ribosome at the start codon: AUG

tRNA binds to the large

subunit of the ribosome

tRNAs begin to move onto the

ribosome

• Unique tRNA for each

codon

• Pool of all tRNAs surround

the ribosomes in the

cytoplasm

What is a tRNA? and what do they carry

Transfer RNA

Separate class of RNA molecules

Carry amino acids to the ribosome during translation

Anticodon:what happens

the tRNA pairs with the mRNA codon and

is complementary. AUG on mRNA → UAC on tRNA

AMEOBA SISTERS