Genetics and Epigenetics

Question 1

What are proteins?

Answer 1

Proteins are chains of amino acids. The
specific combination of amino acids
determines the protein’s structure and
function.

Question 2

What do proteins do? (3)

Answer 2

– Structural: Help to hold cells and tissue together, e.g. collagen.
– Enzymes: Catalyze chemical reactions and aid in metabolism, e.g. monoamine oxidase (MAO).
– Cell signaling: Peptide neurotransmitters, receptors for hormones, neurotransmitters, and cytokines.

Question 3

What is DNA named?

Answer 3

Deoxyribonucleic acid.

Question 4

Where is DNA?

Answer 4

Deoxyribonucleic acid (DNA) is packaged into
chromosomes in the cell’s nucleus.

Question 5

How many chromosomes do humans have typically?

Answer 5

Humans have 23 pairs of chromosomes and receive one per pair from each parent.

Question 6

What is DNA?

Answer 6

The molecule that carries genetic information for the development and functioning of an organism.

Question 7

What are four nucleotide bases that can make up DNA?

Answer 7

– Adenine (A)
– Thymine (T)
– Guanine (G)
– Cytosine (C)

Question 8

Can proteins or DNA be copied?

Answer 8

DNA only.

Question 9

What are genes?

Answer 9

Genes are segments of DNA that code for particular proteins.

Question 10

Difference between genes and proteins?

Answer 10

So genes are like recipes for proteins.
Proteins do all of the work in the cell, but
genes tell the cell how to build those
proteins.

Question 11

What are the pairs of nucleotide bases?

Answer 11

– Adenine (A) and Thymine (T)
– Guanine (G) and Cytosine (C)

Question 12

How are genes organized?

Answer 12

Genes are organized into codons. Each codon is 3 nucleotides long, and ‘codes’ for a specific amino acid.

Question 13

How many codons are there?

Answer 13

There are 43 possible codons (a total of 64), but a lot of them are redundant.

Question 14

Can DNA be directly made into proteins?

Answer 14

No.

Question 15

What is the first step in gene expression?

Answer 15

Transcription.

Question 16

What happens during transcription?

Answer 16

During transcription, a gene is copied into a strand of messenger RNA (mRNA).

Question 17

The sequence of each mRNA strand matches the DNA sequence of that gene. What is the sole exception to this?

Answer 17

The sole exception to this is that in RNA, thymine is replaced by uracil. Since it’s a 1:1 swap, the meaning of the sequence is not affected.

Question 18

What is the second step of gene expression?

Answer 18

Translation.

Question 19

What is translation?

Answer 19

Translation is when mRNA strands are translated into proteins by ribosomes.

Question 20

The 4 steps to gene expression?

Answer 20

1. DNA partially unravels to reveal the structural gene to be transcribed.
2. A messenger RNA is transcribed from one of the exposed DNA strands and carries the genetic code from the nucleus to the cytoplasm of the cell.
3. Once in the cytoplasm, mRNA attaches to a ribosome. The ribosome travels along the mRNA to translate each codon into the appropriate amino acid. All these amino acids become a long protein.
4. Once the ribosome completes translation, it reaches the end and a codon tells it to release the new protein.

Question 21

What is optogenetics?

Answer 21

A transgenic technique that combines genetics and light to control targeted cells in living tissue. Fiber-optic light delivered to selective brain regions such that all neurons exposed to the light respond immediately

Question 22

What is epigenetics?

Answer 22

Changes in gene expression related to experience.

Question 23

What do genetic mutations alter?

Answer 23

Meaning.

Question 24

What do epigenetics alter?

Answer 24

Activity.

Question 25

What is DNA wrapped around
clusters of proteins called?

Answer 25

Histones.

Question 26

What is a combination of protein and
of DNA in chromosomes called?

Answer 26

Chromatin.

Question 27

What does chromatin do?

Answer 27

– Helps regulate the behavior of genes; keeps them in an inactive state.
– If a gene is needed, a section of DNA unfurls, making gene accessible.

Question 28

What are epigenetic changes caused by?

Answer 28

Epigenetic changes are often caused by physical changes in the structure of chromatin.

Question 29

What is histone acetylation?

Answer 29

Histone acetylation leads to relaxation of the chromatin and hence greater transcription (relaxed chromatin).

Question 30

What is histone methylation?

Answer 30

DNA methylation is used to suppress the expression of genes (condensed chromatin).

Question 31

What is the role of the environment?

Answer 31

Can influence gene activity by regulating the behaviour of epigenetic writers and erasers.

Question 32

What helps the brain respond and adapt to the environment?

Answer 32

The addition/removal of acetyl and methyl groups.

Question 33

How does a mother’s high level of grooming/licking affect stress?

Answer 33

Offspring are less anxious, and produce less stress
hormones. Females become high lick/grooming mothers.

Question 34

How does a mother’s low level of grooming/licking affect stress?

Answer 34

– More DNA methylation in a gene encoding the glucocorticoid receptor (mediates stress response).
– Less of the receptor is made in the hippocampus.
– Means less able to turn off stress response = more anxious.