Topic 1 Definitions

Question 1

What are Nucleic acids?

Answer 1

Nucleic acids are the macromolecules that make up the genetic material of all living organisms.

Two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Question 2

What are nucleotides?

Answer 2

Chemical building blocks of DNA and RNA

Single nucleotides consists of:
    A phosphate group
    A five-carbon sugar
    Deoxyribose in DNA
    Ribose in RNA
    A nitrogenous base

Question 3

What are the 5 nitrogenous bases?

Answer 3

Adenine (A),
Thymine (T) IN DNA ONLY
Guanine (G)
Cytosine (C).
Uracil (U) – IN RNA ONLY

Question 4

What categories can nitrogenous bases be placed under?

Answer 4

Pyrimidines
One ring structure
C, T and U

Purines
Two ring structure
A and G

Question 5

What is the structure of DNA?

Answer 5

Double helix

Bases joined by hydrogen bonds

Two strands are antiparallel (run in opposite directions)
3’ end matches with 5’ end of the other strand.

Question 6

What is the structure of RNA?

Answer 6

Ribose sugar

Uracil in RNA (Uracil more stable in single-stranded nucleotides). Pairs with adenine

Question 7

What are the different types of RNA?

Answer 7

Messanger RNA (mRNA)

Carries a copy of DNA’s nucleotide sequence to be translated into proteins.

Ribosomal RNA (rRNA)

Forms ribosomes, the site of the translation of the mRNA into proteins.

Transfer RNA (tRNA)

Carries amino acids to the appropriate position on the mRNA by matching its anticodon sequence to the complementary sequence in the mRNA. The amino acid transferred by tRNA builds the polypeptide chain during translation.

Question 8

Number of chromosomes?

Answer 8

DNA Structure slide 11

Question 9

What makes up Homologous chromosomes?

Answer 9

Paired chromosomes

44 chromosomes form 22 matching pairs : 22 from mother and 22 from father
- autosomes

Genes are found at the same locations (loci) on the pair

Question 10

What are the paired chromosomes for male and female ?

Answer 10

Male - XY

Female - XX

Question 11

What are the three main phases of eukaryotic Cell Cycle?

Answer 11

Interphase: cell doubles its mass and duplicates its entire components

Mitosis: nucleus divides

Cytokinesis: cytoplasm divides- creation of two new cells

Question 12

What is the. interphase?

Answer 12

Divided into three main phases:

G1 (pre-DNA replication)
Cell grows

S (DNA replication)

G2 (post-DNA replication)
cell grows

Question 13

What is the DNA replication process (Initiation phase)?

Answer 13

Separation of parent double strand of DNA into two template strands (Initiation)

Enzyme, DNA helicase unwinds and ‘unzips’ the parent DNA by breaking hydrogen bonds between the base pairs

Creates a replication fork

Question 14

What is the DNA replication process (Elongation phase)?

Answer 14

DNA replication slide 6

Question 15

What is the DNA replication process (termination phase)?

Answer 15

Termination of DNA replication (Termination)

Proteins bind to the termination sequence site in the DNA.

Results in two DNA strands that are exactly like the original.

Double-stranded DNA remain joined by the centromere.

Question 16

What is the male Gametogenesis and its characteristics?

Answer 16

Spermatogenesis.

Location: Occurs in the testicles 
Meiotic division: Equal cell division
Number produced: 4 
Size of gamesters: Sperm smaller than spermatocytes.
Duration: uninterrupted process 
Onset: Begins at puberty
Release: continuos 
End: Lifelong (but reduced with age