DNA/RNA

Question 1

What are the differences between DNA and RNA

Answer 1

DNA sugar is deoxyribose
RNA sugar is ribose

DNA is double helix
RNA is single strand

DNA: Base Thymine present “ACGT”
RNA: Base Uracil present “ACGU”

DNA just found in the Nucleus
RNA found in Nucleus and Cytoplasm

DNA: Only one type
RNA: 3 types (mRNA (messenger), tRNA (ribosomal), rRNA (transfer))

Question 2

What is a Nucleotide

Answer 2

The building blocks of DNA

Question 3

Name the 4 nitrogenous bases contained in DNA and RNA

Answer 3

DNA:
Adenine 
Cytosine 
Guanine 
Thymine  (ACGT)

RNA: 
Adenine 
Cytosine 
Guanine 
Uracil   (ACGU)

Question 4

Name the complementary pairs

Answer 4

DNA:
A = T
G = C

RNA:
A = U
G = C

Question 5

Describe the structure of Double Helix DNA

Answer 5

A single strand of DNA contains 1000s of nucleotides connected

The phosphate and sugar forms the backbone of the strand with bases unattached

But DNA is a double stranded molecule with the strands held together by Hydrogen bonding between complementary bases

The 2 strands are twisted to form a “double helix”

Question 6

Describe the process of DNA replication

Answer 6

Enzymes break the hydrogen bonds in the double helix

The strands are separate exposing the nitrogenous base sequence

Free floating DNA nucleotides match the bases of the original strand and form the complementary strand

These recoil (twist), reforming the hydrogen bond and restoring the double helix

Question 7

Name the 3 steps in protein synthesis and where they occur

Answer 7

Initiation

Transcription — Nucleus

Translation — Cytoplasm

Question 8

Describe Initiation

Answer 8

The DNA double helix unwinds at the site of gene that’s going to produce a protein

Question 9

Outline Transcription

Answer 9

Transcription: The process of copying a segment of DNA into RNA

A section of DNA (gene) opens, exposing the base code for the formation of a protein
Messenger RNA nucleotide match the corresponding base forming mRNA (messenger)

Question 10

Define and outline Translation

Answer 10

Translation: The process in which a cell makes proteins using genetic information carried by mRNA (messenger)

mRNA leaves nucleus and attaches itself to a ribose in the cytoplasm
Here tRNA bring in Amino Acids
The code on the tRNA match the codes on the mRNA so that the amino acids are in the correct sequence to form a protein

Question 11

What does AUG stand for

Answer 11

Codon/triplets

Adenine, Uracil, Guanine

Question 12

Define DNA screening

Answer 12

This is when your DNA is examined for the presence or absence of an altered gene e.g albinism, sickle cell anaemia, cystic fibrosis

Question 13

Define and outline the steps in DNA profiling

Answer 13

Examining DNA for a pattern of DNA fragments, people are identified by their unique pattern

1. DNA is extracted from a cell
2. Restriction enzymes added, which break down the DNA molecule at a specific site
3. Results in a mixture of DNA fragments which differ in weight and size
4. Samples placed in an electrophoresis gell apparatus. Fragments move through a gell driven by an electric field, eventually the process is stopped, using dyes bonds are made visible
5. Separation achieved by lighter particles travelling further + faster to opposite ends
6. The pattern of bonds is unique to each individual and can be used to identify them

Question 14

Where does transcription occur

Answer 14

Nucleus

Question 15

Where does translation occur

Answer 15

Ribosomes