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Biology 20 IB > Genes and Chromosomes > Flashcards

Genes and Chromosomes Flashcards

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
Q

Why do somatic cells divide

A

Repair & regeneration, growth, replacement of dead cells, and embryonic development

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26
Q

Interphase

A

A cell grows (cells spend most of their life in this stage)

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27
Q

Stages of interphase

A

G1: Rapid cell growth, S: DNA replication, and G2: Further cell growth, storage of energy

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28
Q

Phases of Mitosis

A

Prophase, Metaphase, Anaphase, Telophase

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29
Q

Prophase

A

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

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30
Q

Metaphase

A

Spindle fibers attach to centromeres and guide chromosomes to the equator of the cell

31
Q

Anaphase

A

Spindle fibers shorten, pulling sister chromatids to the poles

32
Q

Telophase

A

Chromosomes are in a tight group near the poles, nuclear membrane reforms, spindle fibers break down, chromatids unwind into chromatin, nucleolus reforms

33
Q

Cytokinesis

A

Seperation into two daughter cells

34
Q

cytokinesis in plants

A

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
Q

Cytokinesis in animals

A

An indentation (cleavage furrow) forms due to a ring of contractile proteins. The indentation deepens, splitting the cell into two

36
Q

What determines the lifespan of a cell

A

Telomeres which shorten after each divisioon due to its inability to replicate all DNA

37
Q

Cyclin

A

Proteins that regulate the cell cycle

38
Q

How do cyclins work

A

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
Q

Cyclin D

A

triggers cell to move from G0 to G1 and from G1 to S phase

40
Q

Cyclin E

A

Prepares cell for DNA replication in S phase

41
Q

Cyclin A

A

Activates DNA replication inside nucleus in S phase

42
Q

Cyclin B

A

Promotes assembly of spindle fibers and helps prepare for mitosis

43
Q

Tumor

A

A clump of abnormal cells

44
Q

Benign tumors

A

Abnormal cells that stick to each other and stay localized

45
Q

Malignent tumors

A

abnormal cells that detach and move to other parts of the body, where they spread

46
Q

Carcinomas are also known as

A

malignent tumors

47
Q

Carcinogen

A

chemicals that cause cancer by causing mutations in proto-oncogenes

48
Q

proto-oncogenes

A

normal genes that control the cell cycle but have the possibility to turn into oncogenes

49
Q

Oncogenes

A

potential to cause cancer due to unregulated cell division

50
Q

As a result of meiosis, how many chromosomes does the daughter cell have compared to the parent cell

A

twice as many

51
Q

Germ cells

A

Cells that undergo meiosis

52
Q

What structure does meosis 1 seperate

A

homologous chromosomes

53
Q

What structure does meiosis 2 seperate

A

sister chromatids

54
Q

Prophase 1

A

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
Q

Metaphase 1

A

Spindle fibers guide each tetrad to the equator and line up randomly (independent assortment, another source of variation)

56
Q

Anaphase 1

A

Homologous chromosomes move to opposite poles (centromeres don’t split)

57
Q

Telophase 1

A

chromatids unwind into chromatin, nuclear membrane reforms (redundant step)

58
Q

Cytokinesis 1

A

Haploid cells with homologous chromosomes in seperate cells form

59
Q

Prophase 2

A

Chromatids coil into chromosomes, centrioles migrate to poles, nuclear membrane dissappears, spindle fibers start to form

60
Q

Metaphase 2

A

Spindle fibers guide chromosomes to the equator of each cell

61
Q

Anaphase 2

A

Centromeres split, sister chromatids split to opposite poles

62
Q

Telophase 2`

A

Chromatids unwind into strands of chromatin, spindle fibers break down, nuclear membrane reforms

63
Q

Cytokinesis 2

A

4 haploid daughter cells form

64
Q

spermatogenesis

A

meiosis of sperm

65
Q

oogenesis

A

meiosis of egg

66
Q

Fraternal twins formation

A

When two secondary oocytes are released at the same time and fertilized by two sperm

67
Q

Are fraternal twins genetically identical

A

only to the same extent as regular siblings

68
Q

Identical twins formation

A

A single secondary oocyte is ovulated and fertilized, but zygote splits into two

69
Q

non disjunction event in chromosomes

A

When centromeres don’t split and sister chromatids or homologous chromosomes move to same pole

70
Q

Disorders caused by non-disjunction in autosomes

A

down syndrome, edwards syndrome, pautau syndrome

71
Q

disorders caused by non-disjunction in gametes

A

turner syndrome, klinefelter syndrome, jacob’s syndrome

72
Q

Human genome project duration

A

1990-2003

73
Q

How long is human genome

A

6.4 billion bases long with 23000 genes

Biology 20 IB (6 decks)

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