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Biology 20 IB > Genes and Chromosomes > Flashcards

Genes and Chromosomes Flashcards

(73 cards)

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1
Q

DNA shape difference: prokaryotes and eukaryotes

A

Prokaryotes have circular DNA, eukaryotes have linear DNA

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2
Q

What are histones

A

proteins associated with DNA

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3
Q

Do prokaryotes or eukaryotes have histones

A

Only eukaryotes

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4
Q

Ploidy of prokaryotes vs eukaryotes

A

prokaryotes are haploids, eukaryotes are diploids

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5
Q

Plasmid

A

Accessory DNA that may give prokaryotes a competitive advantage in survival

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6
Q

Name two ways in which plasmids can be useful

A

It can be transferred between cells or even species, and it can be used as a vector (contain a gene that can be added to another organism’s DNA)

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7
Q

What did John Carins contribute

A

He invented a technique for measuring the length of DNA molecules (having them grow on radioactive thymine, where their DNA will leave a mark once the cell is popped)

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8
Q

How many chromosomes do humans have

A

46 or 23 pairs

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9
Q

What are genes

A

sections of DNA that code for specific proteins

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10
Q

Alleles

A

Variations of the same genes

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11
Q

Where do new allels come from

A

mutations

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12
Q

Homologous chromosomes

A

Chromosomes that contain the same genes at the same locuses (specific position)
*Can be different allele of same gene

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13
Q

What is a karyotype

A

A unique set of 46 chromosomes which an individual possesses

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14
Q

Karyogram

A

A diagram of the chromosomes one possesses, where chromosomes are arranged in order from longest to shortest by homologous pairs

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15
Q

Why are karyograms useful

A

It can help diagnose chromosomal disorders

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16
Q

DNA

A

set of instructions on protein synthesis

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17
Q

chromatin

A

long, intertwined strands of DNA wrapped around histones

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18
Q

chromatid

A

one coiled chromosome in preparation for mitosis

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19
Q

autosome

A

chromosomes that are not involved in deteriming an organism’s sex

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20
Q

What chromosomes do men and women have

A

men- XY, women-XX

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21
Q

What chromosome does a sperm and egg have, respectively

A

X or Y, while eggs only contain X chromosomes

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22
Q

Centromere

A

Pinched in center of chromatid

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23
Q

Sister chromatids

A

Identical chromosomes joined at the centromere as a result of DNA replication

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24
Q

How do eukaryotic and prokaryotic cells divide

A

Mitosis and binary fission

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25
Why do somatic cells divide
Repair & regeneration, growth, replacement of dead cells, and embryonic development
26
Interphase
A cell grows (cells spend most of their life in this stage)
27
Stages of interphase
G1: Rapid cell growth, S: DNA replication, and G2: Further cell growth, storage of energy
28
Phases of Mitosis
Prophase, Metaphase, Anaphase, Telophase
29
Prophase
Nuclear membrane and nucleolus disappears, chromatin condenses to form chromosomes, centrosomes start to migrate to the poles of the cell and spindle fibers start to form
30
Metaphase
Spindle fibers attach to centromeres and guide chromosomes to the equator of the cell
31
Anaphase
Spindle fibers shorten, pulling sister chromatids to the poles
32
Telophase
Chromosomes are in a tight group near the poles, nuclear membrane reforms, spindle fibers break down, chromatids unwind into chromatin, nucleolus reforms
33
Cytokinesis
Seperation into two daughter cells
34
cytokinesis in plants
Vesicles bring proteins, enzymes, and glucose to the equation, and fuse to form a cell plate. More substances are deposited at the cells, which help daughter cells form cell walls and eventually split
35
Cytokinesis in animals
An indentation (cleavage furrow) forms due to a ring of contractile proteins. The indentation deepens, splitting the cell into two
36
What determines the lifespan of a cell
Telomeres which shorten after each divisioon due to its inability to replicate all DNA
37
Cyclin
Proteins that regulate the cell cycle
38
How do cyclins work
They bind to enzymes called cyclin dependent kinases which become active and attach phosphate groups to other proteins, activating them to carry out specific tasks for the cell cycle.
39
Cyclin D
triggers cell to move from G0 to G1 and from G1 to S phase
40
Cyclin E
Prepares cell for DNA replication in S phase
41
Cyclin A
Activates DNA replication inside nucleus in S phase
42
Cyclin B
Promotes assembly of spindle fibers and helps prepare for mitosis
43
Tumor
A clump of abnormal cells
44
Benign tumors
Abnormal cells that stick to each other and stay localized
45
Malignent tumors
abnormal cells that detach and move to other parts of the body, where they spread
46
Carcinomas are also known as
malignent tumors
47
Carcinogen
chemicals that cause cancer by causing mutations in proto-oncogenes
48
proto-oncogenes
normal genes that control the cell cycle but have the possibility to turn into oncogenes
49
Oncogenes
potential to cause cancer due to unregulated cell division
50
As a result of meiosis, how many chromosomes does the daughter cell have compared to the parent cell
twice as many
51
Germ cells
Cells that undergo meiosis
52
What structure does meosis 1 seperate
homologous chromosomes
53
What structure does meiosis 2 seperate
sister chromatids
54
Prophase 1
Each pair of homologous chromosomes synapsis (align side by side), forming a tetrad. They may go on to cross over at a chiasmatal (site), which is responsible for variation among species
55
Metaphase 1
Spindle fibers guide each tetrad to the equator and line up randomly (independent assortment, another source of variation)
56
Anaphase 1
Homologous chromosomes move to opposite poles (centromeres don't split)
57
Telophase 1
chromatids unwind into chromatin, nuclear membrane reforms (redundant step)
58
Cytokinesis 1
Haploid cells with homologous chromosomes in seperate cells form
59
Prophase 2
Chromatids coil into chromosomes, centrioles migrate to poles, nuclear membrane dissappears, spindle fibers start to form
60
Metaphase 2
Spindle fibers guide chromosomes to the equator of each cell
61
Anaphase 2
Centromeres split, sister chromatids split to opposite poles
62
Telophase 2`
Chromatids unwind into strands of chromatin, spindle fibers break down, nuclear membrane reforms
63
Cytokinesis 2
4 haploid daughter cells form
64
spermatogenesis
meiosis of sperm
65
oogenesis
meiosis of egg
66
Fraternal twins formation
When two secondary oocytes are released at the same time and fertilized by two sperm
67
Are fraternal twins genetically identical
only to the same extent as regular siblings
68
Identical twins formation
A single secondary oocyte is ovulated and fertilized, but zygote splits into two
69
non disjunction event in chromosomes
When centromeres don't split and sister chromatids or homologous chromosomes move to same pole
70
Disorders caused by non-disjunction in autosomes
down syndrome, edwards syndrome, pautau syndrome
71
disorders caused by non-disjunction in gametes
turner syndrome, klinefelter syndrome, jacob's syndrome
72
Human genome project duration
1990-2003
73
How long is human genome
6.4 billion bases long with 23000 genes

Biology 20 IB (6 decks)

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