Topic 3 - Genetics

Question 1

What is DNA?

Answer 1

deoxyribose nucleic acid
- polymer made up of many subunits (nucleotides)

Question 2

Where is DNA in a cell?

Answer 2

nucleus

Question 3

What is the structure of DNA?

Answer 3

double helix formed by complementary strands of nucleotides held together by hydrogen bonds

Question 4

Describe the relationship between chromosomes, DNA and genes.

Answer 4

DNA is packed tightly into chromosomes which code for genes and traits.

Question 5

What is a nucleotide?

Answer 5

A nucleotide is a subunit in DNA that is made up of 3 parts.
- phosphate
- deoxyribose sugar
- nitrogenous base
they are joined together by sugar phosphate groups which forms a backbone

Question 6

What are the 4 bases in DNA? What base pairs with what?

Answer 6

adenine
thymine
cytosine
guanine
A+T, C+G

Question 7

What bonds hold together the bases in DNA?

Answer 7

hydrogen bonds

Question 8

What is protein synthesis?

Answer 8

how genes make a protein
- transcription (DNA -> mRNA)
- translation (mRNA -> protein)

Question 9

What are the 3 steps involved in transcription?

Answer 9

1. initiation
2. elongation
3. termination

Question 10

What is initiation?

Answer 10

• RNA polymerase binds
  to a part of a gene called the promoter
• which causes the DNA to unwind so the enzyme can read the bases in one of the strands
• The enzyme then makes a strand of mRNA with a complementary sequence of bases

Question 11

What is elongation?

Answer 11

• complementary nucleotides are added to synthesise an mRNA strand
• RNA polymerase reads the unwound DNA strand and builds the mRNA molecule, using complementary base pairs

Question 12

What is termination?

Answer 12

• ending of transcription, and occurs when RNA polymerase
  crosses a termination sequence in the gene
• the mRNA strand is complete, and it detaches from DNA.

Question 13

Where does transcription occur?

Answer 13

nucleus

Question 14

Where does translation occur?

Answer 14

ribosome

Question 15

What is the 1st step of translation?

Answer 15

mRNA moves through the nuclear pore to the cytoplasm

Question 16

What is the 2nd step of translation?

Answer 16

mRNA attaches to the ribosome and the ribosome moves along the mRNA strand reading the codons, translation begings at AUG

Question 17

What is the 3rd step of translation?

Answer 17

transfer RNA (tRNA) molecules ferry the amino acids to the mRNA at the ribosome

Question 18

What is the 4th step of translation?

Answer 18

tRNA links with the ribosome and matches its anticodon with the codon of the mRNA

Question 19

What is the 5th step of translation?

Answer 19

a peptide bond forms between the adjoining amino acids, forming a polypeptide
- tRNA is removed to be used again

Question 20

What is the 6th step of translation?

Answer 20

protein production stops when the STOP codon is reached
don’t write stop
mRNA breaks away from the ribosomes

Question 21

What is mRNA?

Answer 21

messenger RNA

Question 22

How is mRNA paired with DNA? Bases?

Answer 22

Adenine + Uracil
Cytosine + Guanine

Question 23

What is the role of the ribosome?

Answer 23

making proteins

Question 24

What is a codon?

Answer 24

A sequence of three DNA or RNA nucelotides in mRNA

Question 25

What is an anticodon?

Answer 25

sequence of 3 nucleotides in tRNA that corresponds to an mRNA amino acid

Question 26

What is tRNA + role?

Answer 26

transfer RNA - ferry amino acids to the mRNA at the ribosome

Question 27

What is a mutation?

Answer 27

Mutations are changes in genetic material (DNA and genes)

Question 28

When do mutations occur?

Answer 28

1. Errors in DNA replication 2. enduced by mutagens (environmental factors that change DNA)

Question 29

What are mutagens?

Answer 29

- X-rays/radiation - Chemicals, poisons - UV light - Viruses

Question 30

What is point mutation? eg

Answer 30

change in a single base pair of DNA by substitution, deletion, or insertion of a single nitrogenous base. . eg.Cystic fibrosis, sickle cell anemia

Question 31

How is a point mutation different from a deletion/addition mutation?

Answer 31

point mutations is when one base pair is replaced by another and insertions or deletions is when nucleotides are added or removed.

Question 32

How do mutations impact protein synthesis?

Answer 32

1. DNA affected 2. mRNA not copied properly 3. codes for wrong amino acid 4. formation of incorrect protein/part of polypeptide is missing/no functioning protein

Question 33

What are some diseases that are caused by genetic mutations?

Answer 33

Huntington’s Disease Sickle cell anemia

Question 34

How is huntington's disease caused and what are some symptoms?

Answer 34

- Mutations in a gene - DNA segment of cytosine, adenine and guanine that appear multiple times in a row. (normaly 10-35 times, HD 120 times) - depression - stumbling and clumsiness - mood swings

Question 35

How is sickle cell anemia caused and what are some symptoms?

Answer 35

- Only one amino acid changes in the haemoglobin - haemoglobin still functions but it folds differently, changing the shape of the red blood cell, and affecting the way it can carry oxygen. - swelling of hands and feet - Vision problems - delayed growth or puberty