Genetics and Epigenetics

Question 1

What are the primary functions of genetic material?

Answer 1

1. Coding for products necessary within the lifetime of an organism
2. Passing information between cells
3. Passing information from one generation to the next

Question 2

Genome

Answer 2

Complete sequence of nucleotides of the genetic material
- Usually DNA, but can be RNA in viruses

Cell can make distinct products from the genome in response to the environment

Question 3

Genetic Regulation

Answer 3

Affects which genes from the genome are expressed and when, and the products of that gene expression affect the cell’s function and identity

Question 4

Epigenetics

Answer 4

Changes that are made around the genome that do not alter the actual nucleotide sequence, however alter the expression of the genome and the phenotype of an individual
E.g. attachment of chemical markers to genome, histone protein modification, use of non-coding RNAs to influence gene expression
- modifications can be inherited

Question 5

Gene

Answer 5

A nucleotide sequence that can code for a certain product or set of products depending on factors such as alternative splicing and protein modification

Unique unit of heredity

Question 6

Trait

Answer 6

A genetically influenced characteristic encoded by a sequence of nucleotides

Question 7

The Central Dogma

Answer 7

DNA is transcribed to RNA, which is translated to amino acids to form a protein

All living organisms use this method to express their genes (except for retroviruses)

Question 8

Epigenome

Answer 8

Encompasses all of the epigenetic changes that affect gene expression

Question 9

Chromosomes

Answer 9

Arrangement of double stranded DNA sequences in eukaryotic cells
Compact organization to fit within the nucleus inside each cell in your body
Consists of compactly wrapped DNA and protein in heirarchy of organizational levels
- currently unused DNA wrapped tightly around histone proteins

Question 10

Histones

Answer 10

Globular proteins with basic functional groups that give these proteins a net positive charge at normal pH of cells
DNA is slightly negative and wraps tightly around histones

Question 11

Nucleosome

Answer 11

Eight histones wrapped in DNA form this

Nucleosomes wrap into coils called solenoids

Question 12

Supercoils

Answer 12

Solenoids of tightly wrapped nucleosomes wrap into supercoils

Question 13

Chromatin

Answer 13

Entire DNA/protein complex that tightly binds with the help of histones

Chromatin is 1/3 DNA, 2/3 protein by mass, small amount of RNA

Structure is regulated by epigenetic modification and influences gene expression

Question 14

Euchromatin

Answer 14

Chromatin that is uncoiled and more loosely wrapped, nucleotide sequences accessible to cell’s translation machinery

Only coiled during nuclear division when translation has stopped

Cellular machinery that “reads” genetic code acts on this

Question 15

Heterochromatin

Answer 15

Chromatin that is tightly condensed
Not accessibly to cellular machinery, will not be transcribed

Constitutive heterochromatin is permanently coiled

Question 16

Single copy DNA

Answer 16

Nucleotide sequences that code for protein products, represented by only one copy of a nucleotide sequence

Associated with regions of euchromatin that are being actively transcribed

Question 17

Repetitive DNA

Answer 17

Usually contained in non-coding regions of DNA in Eukaryotes, multiple consecutive copies of the same nucleotide sequence and remains tightly coiled in regions of heterochromatin

Question 18

Epigenetic Regulation of Chromatin

Answer 18

Chemical changes to histone proteins help control which sections of DNA are tightly wound and which are accessible to cellular machinery

DNA methylation and histone methylation or acetylation
Methylation- decreases transcription
Acetylation- increases transcription

Question 19

DNA Methylation

Answer 19

Addition of extra methyl group to particular cytosine nucleotides, causes more tight coils which are inaccessible to cellular machinery

Causes decrease in genetic transcription

Question 20

NcRNA

Answer 20

Non-coding RNA contributes to regulation of chemical changes that affect chromatin structure

Question 21

How many chromosomes does the nucleus of a human somatic cell possess normally?

Answer 21

46 chromosomes, 23 homoologous pairs
Traits are the same on the homologous pairs, but actual alleles may be different (different version of gene)

Diploid cell- homologous pairs

Question 22

Haploid

Answer 22

A cell that does not contain homologues

Contains 23 chromosomes without pairs

Question 23

How many chromosomes are there before and after replication in a human somatic cell?

Answer 23

In both occasions, the cell is diploid, meaning it has homologous pairs

In both cases there are also 46 chromosomes, however after replication the chromosomes have identical sister chromatids that are attached at the centromere