Gentics 1

Question 1

What are the 4 bases of DNA

Answer 1

• cytosine
• thymine
• adenine
• guanine

Question 2

What is a double helix of DNA

Answer 2

• DNA consists of 2 strands linked by hydrogen bonding between complimentary bases
• Adenine binds to thymine
• Guanine binds to cytosine

Question 3

How is dna packaged

Answer 3

packaged into nucleosomes

Question 4

How is DNA compacted

Answer 4

condensed during mitosis into individual chromosomes

Question 5

What happens during the cell cycle

Answer 5

cells duplicate contents( chromosomes, macromolecules and organelles etc)

cell divides to form 2 identical daughter cells (mitosis)

Question 6

What is the G1 phase

Answer 6

period of growth and synthesis ( ATP, RNA and organelles) to prepare for cell division

Question 7

What is the S phase

Answer 7

• DNA is copied by DNA polymerase enzymes
• each strand is replicated, the double helix is unwound and strands act as templates
• RNA primer used to initiate DNA replication

Question 8

What is the G2 phase

Answer 8

Second gap phase prepares the cells for entry into mitosis

Question 9

What is the structure of homologous chromosomes

Answer 9

Homologous- one from each parent

Centromere= join sister chromatids and aid attachment during mitosis

Telomeres= non coding ends and protect the coding regions of the genome

Question 10

What are the phases of mitosis

Answer 10

prophase
prometaphase
metaphase
anaphase
telophase

Question 11

What is cytokinesis

Answer 11

complete division of cytoplasm

Question 12

what is a karyotyoe

Answer 12

where mitotic chromosomes can be stained, organised and visualised and help to reveal genetic abnormalities

Question 13

What is meiosis

Answer 13

• a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes (sex cells)
• from diploid (2 sets of chromosomes)
  to a haploid (1 set of chromosomes)

Question 14

what is mendelian inheritance

Answer 14

• applies to simple inheritance traits that can be controlled by a single gene e.g. blood group and cystic fibrosis.
• chance of offspring having a particular characteristic or disease can then be predicted

Question 15

What are alleles

Answer 15

genes come in different forms called alleles which are slight differences in the DNA sequence , two alleles one from each parent

e.g alleles A and a
genotype would be Aa

Dominant (only one needed and capital e.g. A) and recessive (two copies of allele needed and lower case e.g. a)

Question 16

What is DNA gel electrophoresis

Answer 16

method to seperate dna samples based on size, gel acts a molecular sieve, dna is visualised by a fluorescent stain

Question 17

What is polymerase chain reaction ( PCR)

Answer 17

amplify a sequence of DNA ( produce more of them)