DNA replication + Transciption + Translation

Topoisoherase (2)

• Enzyme that relieves the tension of the helix

• enables it to unwind

Helicase

Enzyme that breaks hydrogen bonds that hold the two complementary strands together (unzips them)

Single strand binding proteins

Sticks to each strand of DNA, preventing them from reattaching together

What is Primase and how is it used by DNA?

• Enzyme that lays down RNA primers

• Used by DNA as a marker to build the complementary strands

True or false: DNA polymerase can only move from 5 prime - 3 prime

False, it only moves from 3 prime - 5 prime (on the DNA strand because of the leading strand)

True or false the leading strand is built towards the replication fork (3 prime- 5 prime)

True

True or false a lagging strand is built away from the replication fork continuously

False. Its built away from the replication fork discontinuously

Okazaki fragments

short discontinuous segments of DNA on the lagging strand during DNA replication.

DNA ligase

Joins the gaps with okazaki fragments by creating phosphodiester bonds

True or false: DNA replication takes place during Interphase

False, it takes place during synthesis

Replication bubbles

Bubbles that form on a DNA molecule & cause it to unzip

How do replication bubbles make DNA replication faster

Because there is many happening on 1 strand of DNA

Why can’t DNA leave the nucleus

Its too dangerous, there are things that could damage it

What are 2 advantages of DNA being transcribed into RNA

1. Protects original copy of DNA

2. RNA is an efficient information transferer (Sends DNA codes throughout the cell)

3 types of RNA

1. mRNA (messenger)

2. tRNA (transfer)

3. rRNA (ribosomal)

What is the role of mRNA?

Carries DNA information into the ribosome/cytoplasm

What is the role of tRNA?

Delivers Amino Acids to the ribosomes

What is the role of rRNA?

It is the nucleic acid code and it is apart of the ribosome

What is transcription?

Process where DNA is used to create a complementary mRNA strand

3 stages of transcription

1. initiation

2. elongation

3. termination

True or false: Transcription and translation have the same 3 steps

True

True or false: all 3 stages of transcriptions require enzymes

True

What is a codon?

Code/ sequence of 3 nucleotides

EX. AUG

There can be up to ____ codons found in DNA

64

True or false: Each codon codes for a different amino acid

multiple codons may code for the same amino acid

True or false: codons are not continuous, they can overlapp, or have spaces

False, They are continuous and they DONT have any spaces, and overlapp

True or False: Almost all organisms build proteins using the genetic code table

True

Explain the process of initiation in transcription (2)

1. DNA unwinds

2. An enzyme called RNA polymerase attaches to the promoter region of the gene and starts building the RNA

Now transcription is initated

True or False: binding RNA polymerase to DNA upstream prevents mistakes

True

The bubble spot in transcription is called the _________

promoter

Explain the process of elongation in transcription (3)

1. RNA polymerase moves along the DNA, reading the template strand.

2. It adds RNA nucleotides that are complementary to the DNA.

3. The mRNA strand gets longer as more bases are added.

Explain the process of termination in transcription (3)

1. RNA polymerase reaches a termination signal (a stop sequence on the DNA).

2. It stops building the mRNA.

3. The mRNA is released, and the DNA rewinds.

4 post transcriptional modifications

1. 5 prime cap

2. poly a-tail

3. exons

4. introns

What is the 5 prime capping method?

7-methylguanosine is added to the 5 prime end of the mRNA

What is the poly-a tail tailing method?

Adding a string of 200 Adenine nucleotides to the 3 prime end of mRNA

Why is the capping and tailing method useful?

It protects the mRNA from being digested by the nuclei and phosphates as it exits the nucleus and enters the cytoplasm

Exons

coding regions of DNA

Introns

non coding regions of DNA

How are introns advantageous?

It protects mRNA from mutations

Where does translation take place?

In the ribosome

Explain initiation in translation (2)

1. The ribosome opens up to bind to mRNA

2. Initiation begins when the mRNA reaches the start codon

True or False: The ribosome reads from 5 prime - 3 prime

True

Explain the process of elongation in translation (6)

1. tRNA enters the p-site

2. the anti-codons from tRNA and codons from mRNA match up

3. a second tRNA enters the A-site

4. The amino acids from both tRNA molecules bond together

5. another tRNA enters the p site as the other leaves

6. This process repeats until the ribosome reaches the stop codon

True or false: The mRNA molecule moves from 5 prime to 3 prime during translation

false, it’s the ribosome that moves NOT the mRNA

• the mRNA is stationary

What happens after translation (post translation)

the peptide chain must form a structure

• primary

• secondary

• tertiary

• quatenary