DNA Replicaiton

Question 1

DNA Rep

Answer 1

Process of DNA being copied or replicated before every cell division, so one identical copy goes to each daughter cell

Occurs during interphase stage of Mitosis

Question 2

DNA rep steps

Answer 2

1. Replication starts on DNA molecule called replication origin
2. An enzyme called helicase unzips and unwinds Dna, breaking the hydrogen bonds that joins the base pairs, forming two separate strands
3. Free nucleotides attach to expose based following complementary base pairings
4. Dna polymerase enzymes then joins the new nucleotides to each other by strong covalent bonds
5. New strands wind up forming double helixes with hydrogen bonds connecting them.
6. creates identical dna molecules

Question 3

RNA structure and FUnction

Answer 3

Ribonucleic acid
- Made up of nucleotides contain sugar ribose and the base uracil
- Single Stranded
- RNa is a helper to DNa allowing protein synthesis

Question 4

Types of RNA

Answer 4

Ribosomal RNA
- JOins with proteins made in cytoplasm to form subunits ribosomes
Messenger RNA
- carries genetic information from DNA to ribosomes in cytoplasm where protein synthesis occurs
Transfer RNA
- transfers amino acids to ribosomes where amino acids are joined

Question 5

PRoteins

Answer 5

Composed of amino acids
- Proteins differ due to the number and order of amino acids
- every three bases codes for one amino acid

Question 6

Complementary Base Pairs

Answer 6

Adenine + Thymine/Uracil
Guanine + Cytosine

Question 7

Nucleotide polymerisation

Answer 7

Forming bonds between carbon 3 of the sugar and oxygen atom of the phosphate causing a condensation polymerisation reaction

Question 8

Transcription Steps

Answer 8

1. RNA polymerase attaches to strand of DNA at promoter sequence
2. DNA strands separate exposing nucleotides
3. mRNA pairs with DNA base pairs (Following complementary base pairing)
4. Nucleotides are added til terminator sequence is met
5. mRNA molecule created and leaves nucleus

Question 9

Translation

Answer 9

1. Ribosomes binds with start codon on mRNA
2. tRNA molecule carry amino acid to mRNA
3. complementary anti-codon binds with codon
4. tRNA releases amino acid
5. amino acids forming together creating a polypeptide chain
6. polypeptide chain folds onitself to create 3D shape protein

Question 10

Epigenetics

Answer 10

The study of changes in gene expression without affecting or changing the DNA sequence

Question 11

Acetylation

Answer 11

Addition of acetyl group to the histone
Decrease attraction between DNA and Histones as the chromatin more relaxes/unwinds
DNA is MORE loosely bounded to histone
Enhancing gene Expression
RNA polymerase has greater access to gene = Increased transcription

Question 12

Methylation

Answer 12

Addition of a methyl group to histones
Occuring at CpG sites
Blocking access to genes for RNA polymerases
Inhibits gene expression
Decreasing Transcription

Question 13

Epigenetic change

Answer 13

Factors which changes the gene expression influenced by age, environmental/lifestyle

Question 14

Prophase

Answer 14

Chromosomes condenses
Nuclear membrane breaks down
Spindle fibres form

Question 15

Metaphase

Answer 15

Condensed chromosomes move to the middle of the cell

Question 16

Anaphase

Answer 16

Centromeres divide/degenerate
Chromosomes are moved to opposite ends of spindle

Question 17

Telophase

Answer 17

Two sets of chromosomes uncoils
Nuclear envelopes reforms
Spindle fiber disappears

Question 18

Cytokinesis

Answer 18

Cytoplasm of cell divides into two each containing a nucleus