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GN 311 > Lecture 1 > Flashcards

Lecture 1 Flashcards

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1
Q

Structure of prokaryotic cells

A
  • absent nucleus
  • small cell diameter
  • one circular DNA molecule
  • DNA not complexed with histones in eubacteria; some histones in archaea
  • small amount of DNA
  • no membrane bound organelles
  • no cytoskeleton
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2
Q

Structure of eukaryotic cells

A
  • present nucleus
  • large cell diameter
  • multiple linear DNA molecules
  • DNA complexed with histones
  • large amount of DNA
  • membrane bound organelles
  • cytoskeleton
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3
Q

chromatin

A
  • DNA complexed with histone proteins in eukaryotic cells

- first level of compaction

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4
Q

Diploid eukaryotic cells

A

two sets of chromosomes organized as homologous pairs

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5
Q

Karyotype

A

picture of an individual’s complete set of metaphase chromosomes

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6
Q

Autosomes

A

chromosomes that are the same in males and females; nonsex chromosomes.

humans have 22 pairs of autosomes

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7
Q

allele

A

copy of the gene

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8
Q

locus

A

location of the gene

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9
Q

Telomeres

A

the stable ends of chromosomes

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10
Q

Centromere

A

a constricted region of the chromosome where the kinetochores form and the spindle microtubules attach.

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11
Q

Mitosis

A

Process by which the nucleus divides

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12
Q

Cytokinesis

A

Process by which the cytoplasm of the cell divides

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13
Q

Cell cycle and mitosis

A
  • G1 the cell grows
  • Cells may enter G0, a non dividing phase
  • After the G1/S checkpoint, the cell is committed the dividing
  • In S, DNA duplicates
  • In G2, the cell prepares for mitosis
  • After the G2/M checkpoint, the cell can divide
  • Mitosis and cytokinesis (cell division) take place in M phase
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14
Q

Interphase

A

The nuclear membrane is present and the chromosomes are relaxed

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15
Q

Prophase

A

Chromosomes condense. Each chromosome possesses two chromatids. The mitotic spindle forms

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16
Q

Prometaphase

A

The nuclear envelope disintegrates, and spindle microtubules anchor to kinetochores

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17
Q

Metaphase

A

Chromosomes align along the metaphase plate; spindle-assembly checkpoint

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18
Q

Anaphase

A

Sister chromatids separate, becoming individual chromosomes that migrate toward spindle poles

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19
Q

Telophase

A

Chromosomes arrive at spindle poles, the nuclear envelope reforms and the condensed chromosomes relax

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20
Q

Cytokinesis

A

Cytoplasm divides; cell wall forms in plant cells

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21
Q

disjunction

A

pulling apart of sister chromatids

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22
Q

nondisjunction

A

failure to separate leads to chromosomal aberrations

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23
Q

Prophase 1

A

chromosomes condense, homologous chromosomes synapse, crossing over takes place, the nuclear envelope breaks down, and the mitotic spindle forms

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24
Q

Metaphase 1

Study These Flashcards
A

Homologous pairs of chromosomes line up on the metaphase plate

25
Anaphase 1
The two chromosomes (each with two chromatids) of each homologous pair separate and move toward opposite poles
26
Telophase 1
Chromosomes arrive at the spindle poles
27
Cytokinesis
The cytoplasm divides to produce two cells, each having half the number of chromosomes as the original
28
Interkinesis
In some types of cells, the spindle breaks down, chromosomes relax, and a nuclear envelope re-forms, but no DNA synthesis takes place
29
Prophase II
chromsomes condense, the spindle forms, and the nuclear envelope disintegrates
30
Metaphase II
Individual chromosomes line up on the metaphase plate
31
Anaphase II
Sister chromatids separate and move as individual chromosomes toward the spindle poles
32
Telophase II
Chromosomes arrive at the spindle poles; the spindle breaks down and the nuclear envelope re-forms
33
Cytokinesis
The cytoplasm divides
34
Consequences of Meiosis
- 2 divisions so each cell produces 4 cells | - cells produced are haploids
35
Mendel's Principles of Inheritance
1. dominance - one allele may mask the presence of another at the same locus 2. segregations - alleles segregate from one another during meiosis 3. independent assortment - alleles of different genes segregate independently
36
Why was the pea plant a good choice for genetics?
- ease of cultivation - number of progeny per mating - large number of varieties that were homozygous for the traits studied
37
Gene
a genetic factors that helps determine a characteristic
38
Allele
One of two or more alternative forms of a gene
39
Locus
specific place on a chromosome occupied by an allele
40
Genotype
Set of alleles possessed by an individual organism
41
Heterozygote
An individual organism possessing two different alleles at a locus
42
Homozygote
an individual organism possessing two of the same alleles at a locus
43
Phenotype or trait
The appearance of manifestation of a character - yellow or green
44
Character
An attribute or feature - seed color
45
Monohybrid cross
parents differ in only a single character
46
Attributes of model organisms
- organisms used to help figure out genes - short generation time - manageable number of progeny - adaptability to lab - easy to control - knowledge of genetic system
47
chromosomes may consist of
a single chromatid or two sister chromatids (count the centromeres)
48
Kinetochore
set of proteins that assemble on the centromere providing point of attachment for spindle microtubules
49
Mitosis
process by which the nucleus divides. Chromosome numbers stays the same. Genetically identical cells; diploid
50
How number of chromosomes vary during cell cycle
chromosomes - double between metaphase and anaphase (from 4 to 8) then goes back down to 4 after telophase and cytokinesis
51
How amount of DNA per cell varies during cell cycle
DNA - doubles during the synthesis phase (from 4 to 8). Goes back to four after telophase and cytokinesis
52
Meiosis
- involves two divisions; reductional from 2n to n. equational from n to n. equational goes from a two sister chromatids per cell to two individual chromosomes per cell.
53
How genetic variation generated during meiosis
- due to crossing over in prophase 1 and random distribution of chromosomes in anaphase 1
54
crossing over
breaks in the DNA strand repaired in a way that non sister chromatids are exchanged
55
Random distribution
8 different combinations of chromosomes in the gametes are possible
56
Dominance
one allele may mask presence of the other
57
Segregation
alleles segregate from one another during meiosis
58
Independent assortment
alleles of different genes segregate independently
59
Simple Mendelian inheritance
phenotypes passes in a 3:1 ratio

GN 311 (22 decks)

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