The Nature of Genetic Material

Question 1

genome

Answer 1

entire set of DNA instructions found in a cell, complete (haploid) set of genetic material in a virus, cell, or organelle

Question 2

eukaryotic genome

Answer 2

10 Mb- 100,000 Mb
contained in organelles

Question 3

nucleus

Answer 3

• multiple linear chromosomes
• multiples copies of each chromosome

Question 4

mitochondria

Answer 4

12 kb-2400 kb
circular

Question 5

chloroplast

Answer 5

120 kb-170 kb
- plants only
- circular

Question 6

viruses

Answer 6

infectious particles comprised of a genome surrounded by a protein coat

Question 7

viral genomes

Answer 7

2000 to 1 million bp of RNA or DNA
- linear or circular
- single stranded, double stranded, or segmented
- viral genomes frequently invade the genomes of other organisms

Question 8

prokaryotic genomes

Answer 8

1 chromosome (DNA
0.2-12 Mb
- circular
- found in the nucleoid
-haploid

Question 9

Plasmids

Answer 9

1-200 kbp
- small circles of DNA
- autonomously replicating
- not present in all bacteria

Question 10

How do we visualize chromosomes?

Answer 10

Geimsa dye staining, microscopy, and sorting

Question 11

karyotype

Answer 11

an individuals complete set of chromosomes (46 XX, 46 XY), also refers to the image of a persons organized chromosomes

Question 12

cytogenetics

Answer 12

detect and interpret chromosomal abnormalities
- cells are collected
- cells are grown for a little while to initiate DNA replication
- chromosomes are analyzed

Question 13

prenatal testing

Answer 13

• amniocentesis (16 weeks)
• chorionic vili sampling (11 weeks)
• maternal blood testing (9 weeks)

Question 14

PGD

Answer 14

Preimplantation genetic diagnosis
- can only be used with in-vitro fertilization

Question 15

what do banding patters signify?

Answer 15

eukaryotic (nuclear) chromosome structure

Question 16

cohesions

Answer 16

hold sister chromatids together during mitosis

Question 17

human

Answer 17

22 pairs of autosomes (non-sex)
1 pair of sex chromosomes

Question 18

single chromosome

Answer 18

1 strand of double stranded DNA

Question 19

sister chromatids

Answer 19

2 strands of dsDNA

Question 20

homologous chromosomes

Answer 20

2 chromosomes (4 strands of dsDNA)
- one paternal, one maternal = 2 homologous chromosomes
- We are diploid!

Question 21

chromosome number (n)

Answer 21

n = the number of unique chromosomes in a “set”

Question 22

ploidy

Answer 22

number of complete sets of chromosomes
- specific to a species

Question 23

C-value

Answer 23

amount of nuclear DNA in a gamete (haploid), irrespective of ploidy

Question 24

nucleoid

Answer 24

region that contains condensed DNA/protein complexes; attaches to inner membrane

Question 25

NAPs

Answer 25

nucleoid-associated-proteins that bind to repetitive sequences to form loops of supercoiled DNA

Question 26

Microdomains/Loop domains

Answer 26

help condense bacterial chromosomes
- supercoiling helps pack DNA into smaller spaces

Question 27

topoisomerases

Answer 27

enzymes that overwind and underwind dsDNA

Question 28

How are eukaryotic genomes packaged into cells?

Answer 28

eukaryotic genome packaging is organized

Question 29

nucleosome

Answer 29

a single histone/DNA complex
- fundamental subunit of chromatin

Question 30

5 histone proteins

Answer 30

H2A, H2B, H3, H4 form an octomer
- DNA is wrapped around the octomer 1.65 times
H1 acts as a clamp

Question 31

what does the genome look like inside a cell?

Answer 31

chromosomes occupy specific territories within the nucleus
- likely allows for specific interactions between different chromosomes

Question 32

genomes are dynamic

Answer 32

• sometimes our cells need to “see” the DNA in an uncondensed form (for DNA replication, gene expression, etc.)
• regions of genomes will condense and decondense at different times