DNA and inheritance

Question 1

Describe the structure of DNA

Answer 1

DNA is two long chains made of alternating sugar and phosphate connected by bases, twisted to form a double helix

Question 2

What are the 4 bases?

Answer 2

Adenine and Thymine, Cytosine and Guanine

Question 3

What is genetic code?

Answer 3

The order of bases forms the genetic code, which makes proteins

Question 4

What is the triplet code?

Answer 4

Three consecutive bases codes for one amino acid. The code determines the order in which different amino acids are linked

Question 5

What is genetic profiling?

Answer 5

Genetic profiling is the analysis of an organism’s DNA

Question 6

What is genetic profiling used for?

Answer 6

• identifying suspects from evidence at crime scenes
• in paternity cases
• in comparison between species for classification
• to identify genes that could be associated with disease e.g. CF

Question 7

How is genetic profiling carried out?

Answer 7

The DNA is cut into short pieces that are separated into bands. The pattern of the bands can be compared to show the similarity between samples

Question 8

What are genes?

Answer 8

Genes are sections of DNA molecules that determine inherited characteristics

Question 9

What are alleles?

Answer 9

Alleles are two forms of one gene - a recessive one and a dominant one. They come in pairs

Question 10

What is the difference between a phenotype and a genotype?

Answer 10

One’s genotype is the collection of alleles that determine one’s characteristics, whereas one’s phenotype is the characteristics that are shown due to the genotype

Question 11

what do homozygous and heterozygous mean?

Answer 11

Homozygous are when two alleles for a gene are identical, and heterozygous are when two alleles for a gene are different

Question 12

What is selfing?

Answer 12

Selfing is when a plant self pollinates.

Question 13

What is a genetic disorder?

Answer 13

A genetic disorder is a disorder caused by a mutation to a gene, which is then carried on to offspring

Question 14

How does gene therapy work?

Answer 14

• a working copy of the gene is inserted into a fat droplet
• the fat droplet is inhaled using a nebuliser
• the gene gets into the cell and starts making healthy protein

Question 15

What are the downsides of gene therapy?

Answer 15

• its not guaranteed to work every time
• cells are continually replaced so treatment would have to occur regularly