DNA & Inheritance

Question 1

How many pairs of chromosomes does a human body cell have?

Answer 1

23

Question 2

What is a gene?

Answer 2

A small section of DNA in a chromosome

Question 3

What is DNA?

Answer 3

A double helix polymer

Question 4

What do genes do?

Answer 4

They code for a specific sequence of amino acids in order to make a specific protein. It is the unit of heredity. They contain instructions for individual characteristics.

Question 5

What is the genome?

Answer 5

The entire genetic material of an organism

Question 6

What is DNA made of?

Answer 6

Two long strands of small units that repeat throughout the structure, called nucleotides

Question 7

What does a nucleotide consist of?

Answer 7

Alternating sugar and phosphate sections and one of 4 types of bases attached to the sugar

Question 8

What are the 4 bases called?

Answer 8

Adenine, Thiamine, Cytosine and Guanine

Question 9

How does complimentary base pairing work?

Answer 9

A always joins with T
C always joins with G
Hydrogen bonds connect the bases (2 for C&G, 3 for A&T)

Question 10

What holds the two strands of DNA together?

Answer 10

Attraction between bases

Question 11

How does our body make proteins?

Answer 11

Protein synthesis

Question 12

What is the ‘triplet code’

Answer 12

The sequence of 3 bases that code for an amino acid

Question 13

How can we change the protein made by a gene?

Answer 13

By changing the sequence of bases in the gene

Question 14

Describe the structure of DNA

Answer 14

A polymer consisting of nucleotides made up of phosphate, pentose sugar and a base attached to the sugar. The sugar and phosphate create the backbone (two strands), connected by attractions between complimentary nitrogenous bases, making a double helix shape

Question 15

What are the steps in genetic profiling?

Answer 15

1. Isolation - DNA taken e.g. by cheek swab and extracted from the cell’s nucleus
2. Fragmentation - Chromosomes broken up into shorter segments of DNA by enzymes
3. Separation - DNA fragments placed on gel and put through gel electrophoresis (electric current separating the fragments into size order)
4. Comparison - Results can be compared to other DNA

Question 16

What can genetic profiling be useful for?

Answer 16

Catching criminals (observing whether 2 DNA fingerprints are the same)
Identifying species
Paternity cases (identifying genes)
Identifying disease genes

Question 17

What are the ethical issues associated with genetic profiling?

Answer 17

Invasion of privacy
Misuse of info
Set up crime scenes/mistaken suspects
Family problems

Question 18

How do DNA fragments move in electrophoresis?

Answer 18

Big fragments move slowly and small fragments move further and faster

Question 19

What are alleles?

Answer 19

Different forms/variants/versions of the same gene. Humans have pairs of every gene, so two alleles are present in one gene pair

Question 20

What is the difference between the dominant and recessive allele?

Answer 20

A dominant allele is always expressed, regardless of the identity of the other allele while a recessive allele is only expressed if the other allele is also recessive.

Question 21

What are identical alleles for the same characteristic called (e.g. AA or aa)

Answer 21

Homozygous

Question 22

What are different alleles for the same characteristic called? (e.g. Aa)

Answer 22

Heterozygous

Question 23

What is a phenotype?

Answer 23

An observed characteristic determined by the interaction between the genotype and the environment

Question 24

What is a genotype?

Answer 24

The combination of alleles an organism has

Question 25

Will a person with a heterozygous genotype receive the dominant or recessive phenotype?

Answer 25

Dominant

Question 26

In a Punnett square, what names are given to the generations?

Answer 26

Parents - F0 generation Offspring - F1 generation Their offspring - F2 generation etc.

Question 27

Which Punnett square would give a 50:50 chance of each phenotype?

Answer 27

Rr*rr

Question 28

Which combination of sex chromosomes (X&Y) produce offspring of male or female biological sex?

Answer 28

Female - XX | Male - XY

Question 29

Which sex chromosome does an egg contain?

Answer 29

One X chromosome

Question 30

Which sex chromosome does a sperm contain?

Answer 30

One X OR One Y chromosome

Question 31

What does a Punnett square for gender determination look like?

Answer 31

The mother is always XX The father is always XY 50% of the children are XX (girls) and 50% are XY (boys)

Question 32

What is genetic engineering?

Answer 32

Changing the genetic material of an organism by removing, changing or inserting individual genes from another source to produce a desired characteristic

Question 33

When is genetic engineering used?

Answer 33

Inserting genes into crop plants to give it resistance to herbicides Inserting genes into crop plants to provide additional vitamins Inserting human genes into bacteria to produce human insulin Inserting genes into crop plants to give it resistance to insects

Question 34

What are the advantages of genetically modified (GM) crops?

Answer 34

They generally show increased yields They help provide nutrients missing in diets of people from developing nations (avoiding deficiencies) Popular in some areas of the world and no complications so far

Question 35

What are the advantages of genetic engineering?

Answer 35

Prevents inherited diseases | Improves food production efficiency

Question 36

What are the disadvantages of genetically modified (GM) crops?

Answer 36

Could negatively impact wild flower and insect populations, reducing biodiversity Could have long-term effects on human health after consumption If transplanted genes managed to escape into the natural environment, we could accidentally create a ‘superweed’ that is resistant to herbicides

Question 37

What are some concerns about genetic engineering?

Answer 37

Because it is recent, we do not know the long-term effects it may have Some consider it unethical to create new life forms or move genes between species.

Question 38

What is known as a permanent change in the nucleotide sequence of DNA?

Answer 38

A mutation

Question 39

What is embryonic screening?

Answer 39

Testing an embryo for the presence of a particular allele or other genetic abnormality. It allows couples at risk of transmitting a genetic disease to ensure their future children are unaffected by the disease without going through the process of prenatal diagnosis