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Question 1

to do

Answer 1

watch a video by crash course about it

Question 2

Double Helix

Answer 2

Structure: Two strands held together by hydrogen bonds.

Base Pairing: A with T, G with C.

Nucleotides: Linked by covalent phosphodiester bonds.

Direction: DNA is read from 5’ to 3’ direction.

Question 3

Genetic Information

Answer 3

Replication: DNA copied before cell division

Gene Expression: DNA used to make proteins

Transcription: Copies DNA information into RNA

Translation: Synthesizes proteins based on RNA information

Recombination: DNA exchange between bacterial cells

Question 4

DNA Replication

Answer 4

Unwinds and Strands Separate
- Forms replication fork
- Short RNA primer is produced by
enzyme: Primase
- Starting site for nucleotides to form new strand of DNA

Synthesis of Leading Strand
- DNA polymerase synthesizes
DNA in 5’ to 3’ direction
- Template must read in 3’ to 5’
direction
- Follows replication fork
- Synthesis of leading strand
continuous in 5’ to 3’ direction

Synthesis of Lagging Strand
- DNA polymerase synthesizes
small fragments of DNA :
Okazaki fragments
- Made in 5’ to 3’ direction
- RNA primers are removed and
fragments are joined together
by enzyme Ligase

Question 5

Gene Expression

Answer 5

Transcription: Synthesizing RNA from a DNA template (contains U)

Types of RNA: mRNA, rRNA, tRNA

Question 6

Transcription - Initiation

Answer 6

RNA polymerase binds to gene at the promoter site

DNA strands are separated to expose the template strand

RNA polymerase begins synthesizing RNA from the template strand

The template strand is read in the 3’ to 5’ direction, allowing RNA synthesis in the 5’ to 3’ direction

Question 7

Transcription - Elongation

Answer 7

RNA polymerase moves along the DNA template, unwinding DNA and adding RNA nucleotides

Question 8

Transcription - Termination

Answer 8

RNA polymerase encounters a termination signal in the DNA sequence.

RNA polymerase detaches from the DNA template, releasing the newly synthesized RNA molecule

Question 9

Genetic Code

Answer 9

Codons: Sets of 3 nucleotides, specify amino acids

Stop Codons: UAA, UAG, UGA.

Question 10

Translation - Initiation

Answer 10

Small ribosomal subunit binds to mRNA at the start codon (AUG)

Initiator tRNA carrying methionine (formyl methionine in prokaryotes) binds to the start codon in the ribosome’s P site

Ribosome joins amino acids together by peptide bond

Question 11

Translation - Elongation

Answer 11

tRNA carrying complementary anticodon binds to mRNA codon at the ribosome’s A site

Peptide bond forms between the amino acid on the tRNA in the A site and the growing polypeptide chain

tRNA in the P site moves to the E site and exits the ribosome

New tRNA carrying the next amino acid enters the vacant A site and the polypeptide chain grows as each amino acid is added