Topic 3: DNA and Inheritance

Question 1

What is an allele?

Answer 1

A variety of a gene

Question 2

What is the genotype?

Answer 2

The genes present for a trait.

Example: BB, Bb, bb

Question 3

What is a phenotype?

Answer 3

The visible characteristic.

Example: blue eyes, curly hair, red flowers.

Question 4

What is a dominant allele?

Answer 4

An allele that shows in the phenotype whenever it is present.
(shown as capital)

Question 5

What is a recessive allele?

Answer 5

An allele that is hidden when a dominant allele is present.

Shown as lower case

Question 6

What is a homozygous allele?

Answer 6

A genotype in which the two alleles for the characteristic are identical. (AA or aa)

Question 7

What is a heterozygous allele?

Answer 7

A genotype in which the two allele for a particular characteristic are different. (Aa)

Question 8

What is DNA?

Answer 8

DNA molecules carry the genetic code that determines the characteristics of a living organism.

Question 9

What is a gene?

Answer 9

A gene is a section of DNA that codes for a specific protein.

Question 10

What is a chromosome?

Answer 10

Long threads of DNA, each made up of many genes.

Question 11

Where is a chromosome located?

Answer 11

In the nucleus of a cell.

Question 12

What is the structure of the DNA molecule?

Answer 12

Double helix. (Two strands twisted together in a spiral.

Question 13

What is the backbone of each DNA strand made of?

Answer 13

Sugar and phosphate molecules.

Question 14

What are the 4 bases that occur in DNA molecules?

Answer 14

Thymine T
Adenine A
Guanine G
Cytosine C

Question 15

What are the complementary base pairings?

Answer 15

Thymine - adenine (T-A)

Guanine - cytosine (G-C)

Question 16

What is the triplet code?

Answer 16

A code of three bases. Amino acids are then joined in this order to make the protein.

Question 17

What is selfing?

Answer 17

When gametes from the same parent fuse. (example: where pollen from one plant lands on the stigma of the same plant)

Question 18

How do you construct a Punnett square?

Answer 18

Determine the parental genotypes
Split the alleles for each parental type and add them into your Punnett square around the edges.
Work out the new possible genetic combinations inside the Punnett square.
Use this to answer the question. You may be asked to comment on the proportion of different allele combinations in the offspring, calculate a probability ratio, or just determine the phenotypes of the offspring.

Question 19

How is homozygous recessive written?

Answer 19

aa

Question 20

Hoe is homozygous dominant written?

Answer 20

AA

Question 21

How is heterozygous written?

Answer 21

Aa

Question 22

Which chromosome determines the sex?

Answer 22

23rd

Question 23

What is the Punnett square for sex determination?

Answer 23

X X
X XX XX
Y XY XY Always 50/50

Question 24

What is genetic profiling?

Answer 24

A method of comparing DNA.

Question 25

What is the process of genetic profiling?

Answer 25

By cutting DNA into fragments and comparing the fragments with each other.

Question 26

What are 3 examples of genetic profiling?

Answer 26

- Paternity testing (see who is biologically a child's parent) - Forensic identification (matching a criminal with the DNA left on a crime scene) - Matching an organism's DNA to classify it

Question 27

What are 2 benefits of genetic profiling?

Answer 27

- It can help catch criminals | - It can be used to identify the presence of disease-causing genes

Question 28

What is an ethical issues surrounding genetic profiling?

Answer 28

It can be used against people by insurance companies based on a person's predisposition to certain diseases.

Question 29

What is the structure of DNA and what is it made out of?

Answer 29

It is a polymer made of many nucleotide monomers | It is made of 2 strands in the shape of a double helix

Question 30

What is the genome?

Answer 30

The entire genetic material of an organism. The human genome being the entire genetic material that makes a human.

Question 31

How does the sequence of DNA affect the protein made in protein synthesis?

Answer 31

DNA is a triplet code where 3 bases code for one amino acid and the order of amino acids determine the protein produced.

Question 32

What is the F1 generation?

Answer 32

The offspring produced when 2 organisms are bred together.

Question 33

What is the F2 generation?

Answer 33

The offspring produced from the F1 generation.

Question 34

What is genetic engineering?

Answer 34

Altering the genome of an organism.

Question 35

What is a transgenic organism?

Answer 35

An organism that contains foreign DNA.

Question 36

What is genetic modification?

Answer 36

Something that allows genetic material from one organism to be transferred into the DNA of another.

Question 37

What is an advantage of genetic modification? (within plants)

Answer 37

genes for disease resistance can be transferred to crop plants to increase yield.

Question 38

What is a disadvantage of genetic modification? (within plants)

Answer 38

Creation of super weeds if the herbicide resistance genes are taken up by weed species.

Question 39

What is a herbicide?

Answer 39

a substance that is toxic to plants.