Genetics

Question 1

Describe the process of evolution by natural selection.

Answer 1

1. Random mutations in DNA sequence cause
2. genetic variation in the population,
3. which makes some individuals be born with different characteristics that
4. make them more adapted to their environment,
5. increasing their fitness
6. and thus their chances of surviving.
7. These individuals are more likely to reproduce
8. and pass on
9. the alleles that increase their fitness
10. to their offspring.

Question 2

Somatic cell

Answer 2

Not a germ cell: A body cell with both pairs of chromosomes.

Question 3

Gamete

Answer 3

Sex cell (sperm or egg). Cell with half the number of chromosomes that will combine with another sex cell to make a new organism in sexual reproduction.

Question 4

Flagellum

Answer 4

A tail on a cell (for example, on a sperm or bacterial cell)

Question 5

Sex chromosomes

Answer 5

Chromosomes (X and Y) that determine sex. XX is female and XY is male.

Question 6

Germ cell

Answer 6

Another name for a gamete. A sex cell (sperm or egg). Cell with half the number of chromosomes that will combine with another sex cell to make a new organism in sexual reproduction.

Question 7

Meiosis

Answer 7

Cell division that produces FOUR NON-IDENTICAL cells with HALF the number of chromosomes.

Question 8

Diploid

Answer 8

Having two of every chromosome. Chromosomes come in pairs.

Question 9

Haploid

Answer 9

Having only one of each chromosome.

Question 10

Chromosomes

Answer 10

One single molecule (double helix) of DNA.

Question 11

Translation

Answer 11

The production of a complementary strand of mRNA from DNA in the nucleus.

Question 12

Transcription

Answer 12

The production of a protein using the instructions of DNA. The order of the bases on the DNA (in the gene) tell the cell which order to put the amino acids in.

Question 13

Central dogma

Answer 13

DNA ⟶ mRNA ⟶ protein ⟶ characteristic

Question 14

Mutation

Answer 14

Change in a DNA sequence.

Question 15

How mutations cause variation

Answer 15

1. mutation
2. changes base(s) in DNA sequence
3. means the sequence of bases in mRNA
4. which means that a different sequence of amino acids will be put together by the ribosome during translation
5. and therefore the three-dimensional structure of the protein will be different
6. which means its functionality will be affected.

Question 16

Centromere

Answer 16

Central part of a chromosome that holds the two arms of the chromosome together.

Question 17

Chromatid

Answer 17

One copy of a chromosome that is made during replication in preparation for cell division and is attached to (part of) a chromosome. Chromatids will be pulled apart to opposite sides of a cell during mitosis.

Question 18

Replication

Answer 18

Copying of DNA in which the strands of the double helix are unwound and then complementary basepairs are matched against the bases in the old strands.

Question 19

Allele

Answer 19

One of multiple versions of a gene. It differs from other alleles of the same gene by mutations (changes) in the DNA sequence.

Question 20

Carrier

Answer 20

A healthy person that has one allele for a recessive disease. (A person heterozygous for a disease gene.)

Question 21

Heterozygous

Answer 21

Having two different alleles.

Question 22

Homozygous

Answer 22

Having two of the same allele.

Question 23

Dominant allele

Answer 23

An allele that causes a characteristic if even only one is present.

Question 24

Recessive allele

Answer 24

An allele that needs to come together in a pair in order to cause a characteristic.