Module 2:7 Chromosomes and Organelle DNA

Question 1

Chromosome

Answer 1

One double-stranded DNA molecule

Hold a lot of noncoding DNA

Counted by centromeres

Question 2

Supercoiling of DNA

Answer 2

Winding of DNA strands, this can reduce the size of DNA by 10000x

(In eukaryotes and prokaryotes)

Question 3

Prokaryotic Chromosomes

Answer 3

Singular and circular (typically)

Contained in nuclei and anchored together by scaffolding proteins (not histones)

Question 4

Plasmids

Answer 4

Small circular DNA molecules that replicate separately from the bacterial chromosome

Replicate by rolling circle

Question 5

Bacterial Cell Division

Answer 5

DNA undergoes theta replication.
Chromosomes assort to opposite sides of the cell.
They are anchored by their ORI to the poles of the cell by proteins
So when cell divides, each new cell has an identical copy of the original chromosome

Question 6

eukaryotic chromatin

Answer 6

DNA complexed with histones to form chromosomes

Question 7

chromatin

Answer 7

DNA complexed with proteins, but may not be tightly wound cDNA exists like this for most of the cell cycle)

Question 8

nucleosome

Answer 8

Bead-like structure in eukaryotic chromatin, composed of short length of DNA wrapped around a core of history proteins. Structure of nucleosome affects the chromosomal capacity for modification.

Question 9

histone-DNA complex structure

Answer 9

Histones are wrapped twice by DNA. Linker DNA connects multiple complexes

Question 10

effects of longer linker strands/less tight binding between histones

Answer 10

Enzymes can more easily access the DNA between the histones to either cut or transcribe it

Can be caused by acetylation

Question 11

30nm (diameter fiber)

Answer 11

The fiber of chromatin that forms when nucleosomes coil due to the association of histones

Question 12

300nm (diameter) fiber

Answer 12

Compressed loops of 30nm fiber

Question 13

chromatosome

Answer 13

nucleosome + H1 histone

Question 14

interphase chromosomes are _____ bound

Answer 14

Loosely

Question 15

mitotic chromosomes (during cell replication) are ____ bound

Answer 15

Tightly

Question 16

modification of histones

Answer 16

Changes the nature of chromatin

Acetylation, deacetylation, methylation, ubiquitnation, and phosphorylation

Question 17

heterochomatin

Answer 17

Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.

@ centromere, telomeres, and others

Few genes, mostly non-coding regions

Question 18

euchromatin

Answer 18

The less condensed version of eukaryotic chromatin that is available for transcription

@ chromosomal arms

Contains genes; many unique sequences that are usually coding (are transcribed)

Crossing over occurs in these regions

Question 19

experiement: chromatin structure alteration during transcription

Answer 19

Chicken erythroblastes: the sensitivity of DNA to digestion by DNAse 1 changed throughout transcription because DNAse 1 digestion is correlated with gene expression

Question 20

centromere

Answer 20

Region of a chromosome where the 2 sister chromatids attach.

No centromere = chromosomal loss

Question 21

telomere function

Answer 21

Protects chromosome ends

Prevents chromosomes sticking together

Shelterin protection or t-loop

Question 22

if DNAse I can cleave a gene, it is a gene that ____ be transcribed

Answer 22

Will

Question 23

melting temperature of DNA

Answer 23

The higher the temperature two different organisms’ DNA is raised to and it still reanneals, the more closely related the organisms

Question 24

Gene density is higher in _____

Answer 24

Euchromatin

Question 25

gene density is lower in _____

Answer 25

Heterochromatin

Question 26

Diploid

Answer 26

Organism/cell with 2 sets of chromosomes or twice the haploid number 2n Eukaryotes

Question 27

homologous chromosomes

Answer 27

A pair of chromosomes that have the same sequence of genes and the same structure Code for different alleles

Question 28

haploid

Answer 28

Organism/cell having only one complete set of chromosomes n

Question 29

identification of chromosomes is based on ______

Answer 29

Centromere location

Question 30

submetacentric chromosome

Answer 30

Centromere 1/3 away from top of the chromosome

Question 31

metacentric chromosome

Answer 31

Centromere in middle of chromosome

Question 32

telocentric chromosome

Answer 32

Centromere at terminal end of chromosome (telomere location)

Question 33

acrocentric chromosome

Answer 33

Centromere 1/8 away from terminal end of arm

Question 34

after replication, each chromosome consists of _____

Answer 34

2 identical sister chromatids

Question 35

meiosis I

Answer 35

how your body makes a new nucleus for its cells; equal partitioning of homologous chromosomes to each daughter cell. 1/2 of the pair goes to each of two cells (XX) to (X) (X)

Question 36

meiosis II

Answer 36

equal partitioning of sister chromatids into each of 4 daughter cells. (X) (X) to (I) (I) (I) (I)

Question 37

cytokinesis

Answer 37

division of the cytoplasm (including organelles)

Question 38

cells are cloned in _____

Answer 38

asexual/somatic cell production

Question 39

endosymbionts

Answer 39

bacteria that evolved to live within other cells as organelles; they rely on the other cell to function

Question 40

chloroplastic genome

Answer 40

typically one circular chromosome in many copies. Genes encode rRNA, tRNA, ribosomal proteins associated with photosynthetic proteins. low mutation rate; slow to evolve

Question 41

mitochondrial genome

Answer 41

typically one circular chromosome on many copies mutation rate fairly high (higher in animals and inc with age) all mitochondrial DNA inherited from mother

Question 42

organelle genome inheritance

Answer 42

uniparentally (mitochondria always passed mother to offspring) one cell may contian many variations of mutated mitochondria (heteroplasmy) or just one variation (homoplasmy) , based on how they are randomly assorted during mitosis. can transfer horizontally

Question 43

mixed copies of mutant and nonmutant chloroplasts in plants results in:

Answer 43

variegation

Question 44

diseases associated with mitochondrial inheritance

Answer 44

typically associated with the loss of oxidative phosphorylation (proton gradient) capabilities

Question 45

acetylation

Answer 45

makes proteins more negative looser binding between negatively charged DNA and histones longer linker DNA

Question 46

deacetylation

Answer 46

reversion of acetylation

Question 47

methylation

Answer 47

causes silencing of DNA sequence