Test 7: Genetics

Question 1

What is DNA?

Answer 1

DNA is the hereditary blueprint for all biological traits and processes. It is the original copy of a gene.

Question 2

What structure is DNA?

Answer 2

Double helix structure.

Question 3

What is chromatin?

Answer 3

It is the mass of DNA in a nondividing cell.

Question 4

What happens when the cell divides?

Answer 4

Chromatin DNA contracts itself into compact “sticks” called chromosomes.

Question 5

What is a karyotype?

Answer 5

It is the representation of a complete set of chromosomes.

Question 6

How many chromosomes do humans have?

Answer 6

We have 46 chromosomes or 23 pairs of homologous chromosomes (one set from each parent).

Question 7

What does DNA contain?

Answer 7

• Sugars, phosphate groups (sugar phosphate backbone)

- Nitrogen bases (A, T, G, C)

Question 8

Where do we find DNA?

Answer 8

In the nucleus.

Question 9

What is mRNA?

Answer 9

A duplicate copy of a gene.

Question 10

Where do we find mRNA?

Answer 10

In the nucleus and cytoplasm.

Question 11

What structure is mRNA?

Answer 11

Single strand structure.

Question 12

What are the mRNA bases?

Answer 12

A-U G-C

Question 13

Where do we find tRNA?

Answer 13

In the cytoplasm.

Question 14

What are the tRNA bases?

Answer 14

A-U G-C, tRNA carried bases in triplets.

Question 15

What structure is tRNA?

Answer 15

Clover shaped.

Question 16

What is a gene?

Answer 16

It is a segment of DNA.

Question 17

What do genes do?

Answer 17

• Provide the instructions for making proteins.

- Will code for a series of amino acids which will make a functional protein.

Question 18

Why is the genetic code said to be a triplet code?

Answer 18

Because a series of 3 nitrogen bases comprised of some combination of A, T, G or C, will code for a particular amino acid.

Question 19

What’s a genome?

Answer 19

It is a complete set of genes. The A-T-G-C sequence for all genetic information.

Question 20

What do eukaryotic cells contain?

Answer 20

They contain a membrane bound nucleus which contains DNA.

Question 21

How many proteins does the human body contain?

Answer 21

30 000 - 50 000

Question 22

Give examples of specific roles proteins play in the body.

Answer 22

• Hormones
• Antibodies
• Enzymes
• Hemoglobin

Question 23

What do proteins determine?

Answer 23

Proteins determine the character traits of an organism.

Question 24

What are the building blocks of proteins?

Answer 24

Amino acids.

Question 25

What is transcription and where does it occur?

Answer 25

• From DNA to mRNA

- Inside the nucleus

Question 26

What are the steps during transcription?

Answer 26

• The double helix DNA unwinds
• A copy of a gene is made (random free bases pair up with the bases of DNA to copy)
• The mRNA can now leave the nucleus, into the cytoplasm

Question 27

What is translation and where does it occur?

Answer 27

• From mRNA to protein

- On the ribosomes

Question 28

What are the steps during translation?

Answer 28

• mRNA carries the instructions of the gene to the ribosomes
• The ribosome slides among the mRNA and reads each triplet
• Each triplet encodes for one different amino acid
• tRNA brings each amino acid to the corresponding mRNA triplet
• When the amino acids are linked, the RNA is released

(ribosome allows tRNA and mRNA to link, ribosome slides along mRNA and reads it in triplets, tRNA links and codes an amino acid)

Question 29

What is folding?

Answer 29

The synthesized protein is released from the ribosome, folds into its functional shape and can now perform its role in the body.

Question 30

What is heredity?

Answer 30

The transmission of characteristics from parent to offspring.

Question 31

What are phenotypes?

Answer 31

Physical traits of the organism.

Question 32

What is a genotype?

Answer 32

Type of alleles (2) for a specific gene.

Question 33

What’s an allele?

Answer 33

A form of gene.

Question 34

What’s a dominant allele?

Answer 34

It takes priority, it’s visible. (uppercase letter)

Question 35

What’s a recessive trait?

Answer 35

It doesn’t take priority, it’s not visible. (lowercase letter)

Question 36

What’s homozygous?

Answer 36

Two of the same alleles. (HH) (hh)

Question 37

What is heterozygous?

Answer 37

Two different alleles. (Hh)

Question 38

What’s crossbreeding?

Answer 38

The exchange of gametes between 2 different individuals during sexual reproduction.

Question 39

What’s a monohybrid cross?

Answer 39

Cross with one trait.

Question 40

What’s a dihybrid cross?

Answer 40

Cross with two traits.

Question 41

What’s pure line?

Answer 41

Individuals who for a specific character trait only produce offspring with the same trait.

Question 42

What’a a hybrid?

Answer 42

Individual obtained by crossbreeding 2 genetically different individuals.

Question 43

What’s the Law of Segregation of Alleles?

Answer 43

Gametes carry only one allele for a gene.

Question 44

What’s Mendel’s Law of Independent Assortment?

Answer 44

When gametes are formed, alleles are randomly assorted. (no link between alleles)

Question 45

What’s a punnett square?

Answer 45

Technique for calculating the probability of different progeny.