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CCEA AS Biology Unit 1 > U1T6 - Keywords > Flashcards

U1T6 - Keywords Flashcards

1
Q

Cell Cycle

A

The cycle of growth + division of a cell. Formation of new cells + contents, growth, mitosis + dividing into 2.

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2
Q

Mitosis

A

1 cell division where 2 daughter cells are produced with same number of chromosomes as parent cell. Genetically identical. Only a part of the cell cycle. Nuclear division following DNA replication during S phase. Parent cell = haploid/diploid. Homologous chromosomes don’t associate during prophase. No chiasmata. Asexual reproduction. Occurs in all organisms.

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3
Q

Cytokinesis (Mitosis)

A

When the cell physically divides into 2 at the end of mitosis forming 2 genetically identical daughter cells, each with an identical chromosome makeup to parent cell. Division of cytoplasm.

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4
Q

G

S

A

Gap Phase

Synthesis Phase

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5
Q

Interphase

A

Longest part of cell cycle. e.g. human embryo development = 24 hours.

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6
Q

G1 Phase

A

Gap/Growth Phase. Period of rapid cell growth when new organelles are synthesised.

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7
Q

S Phase

A

Synthesis of new DNA, DNA in cell doubles, chromosomes replicate.

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8
Q

G2 Phase

A

Gap/Growth Phase. Centrioles replicate + microtubules start to construct spindle. ATP stores built up.

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9
Q

G0 Phase

A

Point where cell is resting in unfavourable conditions. Can last days, weeks or years. Still does normal processes.

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10
Q

Apoptosis

A

When a cell is destroyed at a cell cycle checkpoint if growth phases haven’t been carried out properly.

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11
Q

Cancer

A

Cell division which is out of control.

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12
Q

Prophase (Mitosis)

A

Longest stage in mitosis. Chromatin in nucleus becomes shorter + thicker, it has become condensed + visible. It has more strength, preventing damage during mitosis.

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13
Q

Metaphase (Mitosis)

A

Short phase. 2 Chromatids move towards cell equator. Attach themselves to microtubules of spindle fibre by centromere.

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14
Q

Anaphase (Mitosis)

A

Short phase. Centromeres which hold each pair of chromatids together divide. Chromatids move to poles, centromere first by spindle fibres contracting. As they contract, they shorten + pull chromatids apart to opposite ends of the cell.

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15
Q

Telophase (Mitosis)

A

Sister chromatids end at opposite poles of cell + become chromosomes which decondense + become less visible. Nucleolus reappears + nuclear membrane reforms around 2 chromosome groups. Spindle disappears + there are now 2 distinct nuclei.

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16
Q

Mitotic Poison

A

Drug which inhibit microtubule formation which are structures that make up cell spindle which moves + separates chromatids, therefore inhibiting cell division at M phase of cell cycle.

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17
Q

Metastasize

A

Grow + spread throughout the body.

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18
Q

Antimetabolites

A

Chemical that inhibits the use of a metabolite which is a chemical that’s part of animal metabolism. Some of first effective chemotherapeutic agents discovered. Made up of folic acid, pyrimidine or purine chemicals. Have similar structures to naturally occurring molecules used in nucleic acid of DNA/RNA synthesis.

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19
Q

Nucleosome

A

Length of DNA double helix containing 200 base pairs wound around a bead of histone protein.

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20
Q

Chromosomes

A

Structures which provide continuity between each cell generation. Made of DNA. Only seen when cell is dividing.

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21
Q

Karyotype/karyogram

A

Photomicrograph which shows the number + appearance of chromosomes in a cell.

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22
Q

Diploid

A

Chromosomes are arranged in pairs within their cells. 2 copies of each chromosome (2n)

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23
Q

Homologous Pairs

A

Diploid cells which have chromosomes arranged in pairs within their cells. Maternal + paternal chromosomes paired. Identical in gene context + order.

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24
Q

Allele

A

When chromosomes of a homologous pair contain the same gene in a different form e.g. blue eyes + green eyes/dominant + recessive.

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25
Q

Meiosis

A

Type of cell division which produces gametes with haploid chromosomes so a diploid zygote is produced at fertilisation. It is a reduction division. 2 cell divisions. daughter cells. Parent cell = diploid. Bivalents formed form homologous chromosomes pairing. Chiasmata form between chromatids of homologous chromosomes during prophase I. Daughter cells genetically different. Occurs in animals + plants.

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26
Q

Zygote

A

Fertilised egg.

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27
Q

Haploid

A

Half chromosomes. 1 copy of each chromosome (n)

28
Q

Paternal chromosomes

A

Chromosomes from a father in sperm.

29
Q

Maternal chromosomes

A

Chromosomes from a mother in the egg.

30
Q

Heterozygous

A

2 different alleles (Dominant + Recessive) e.g. Bb

31
Q

Homozygous

A

Same allele (Both Dom/Both Recessive) e.g. BB/bb

32
Q

Ploidy

A

Number of sets of homologous chromosomes in cell.

33
Q

Bivalent

A

Matched pair of maternal + paternal chromosomes (pair of homologous chromosomes) Consists of 4 strands, 2 chromosomes split into 2 chromatids.

34
Q

Prophase 1

A

Synapsis, crossing over, nucleolus disappears + nuclear membrane breaks down. In animal cells, centrioles migrate to opposite cell poles. Longest + most complex stage in Meiosis 1.

35
Q

Synapsis (Meiosis)

A

When maternal + paternal chromosomes come together in homologous pairs, chromosomes shorten + thicken by coiling, then condensing + becoming visible.

36
Q

Chiasmata

A

The point where the exchange of chromatid material occurs during prophase 1. Singular = chiasma. Means join. Where chromatids cross over each other in a cell performing meiosis. Chromatids break + rejoin here. Number of chiasma on chromosome pair is variable (longer = more) Genetic material is exchanged so gamete variation is increased.

37
Q

Crossing Over

A

As chromosomes pair up, they shorten + twist around each other, causing tension. Sections of chromatid may break off + exchange with corresponding sections of different chromatid.

38
Q

Metaphase 1

A

Microtubules of spindle attach to chromosome centromeres. Bivalents aligned along cell equator. Random arrangement relative to orientation of other bivalents.

39
Q

Anaphase 1

A

Chromosomes in each bivalent separate. Centromeres are attached to spindle fibres, the microtubules of these contract + pull homologous chromosomes apart. Each pole receives haploid number of chromosomes.

40
Q

Telophase 1

A

Chromosomes reach opposite poles of spindle, still appearing as 2 chromatids. Nuclear envelope forms around each group of haploid chromosomes. Spindle fibres disappear. Chromosomes stay in condensed for and meiosis 2 occurs. The homologous chromosomes are separated into 2 intermediary daughter cells.

41
Q

Prophase 2

A

Centrioles, where present, divide + move to opposite poles. New spindle fibres develop at right angles to old meiosis 1 spindle. Nucleolus disappears + nuclear envelope disappears.

42
Q

Metaphase 2

A

Chromosomes arrange themselves on equator of new spindle. Each chromosome is attached to spindle by centromere.

43
Q

Anaphase 2

A

Centromeres divide + microtubules of spindle fibres contract to pull 2 chromatids to poles, centromere first. This is the point where chromatids are separated.

44
Q

Telophase 2

A

When chromosomes reach poles, they unwind + become indistinct. Nuclear envelope + nucleolus reformed. Spindle disappears + cells divide to give 4 haploid cells, known as a tetrad.

45
Q

Tetrad

A

Set of 4 haploid cells.

46
Q

Independent Assortment

A

The way each chromosome lines up on the equator during metaphase 1, which is totally independent of how other pairs line up. (Which pair is closer to a particular pole)

47
Q

Centromere

A

The point on a chromosome by which it is attached to a spindle fibre during cell division.

48
Q

Nuclear Spindle

A

Spindle fibres which form during mitosis/meiosis. Responsible for moving + segregating chromosomes during nuclear division.

49
Q

Chromatid

A

A thread-like strand into which a chromosome divides during cell division. Each contains a double helix of DNA.

50
Q

Centriole

A

Small cylindrical organelle near nucleus in animal cells. Involved in development of spindle fibres in cell division.

51
Q

Asters

A

Structure formed in cell during mitosis, composed of astral rays radiating about the centrosome.

52
Q

Nucleolus

A

Small dense spherical structure in the nucleus of a cell during interphase.

53
Q

Reduction Division

A

The first division of meiosis in which the number of chromosomes is reduced to half the original number.

54
Q

Recombinants

A

DNA molecules formed by lab methods of genetic recombination to bring together genetic material from multiple sources. (Genetic Variation) The 2 chromatids which are involved in crossing over.

55
Q

Dictyosomes

A

Golgi bodies that form the golgi apparatus.

56
Q

Tumour

A

Large mass of cancer cells. Can be benign or malignant.

57
Q

Benign

A

Tumours which can stop growing + are encapsulated in fibrous sheath + don’t travel to other locations in body.1

58
Q

Malignant

A

Tumour which continues to grow unchecked + uncontrolled.

59
Q

Gene

A

Specific lengths of DNA along strand which code for protein synthesis. Unit of hereditary.

60
Q

Gene loci

A

Location of the gene.

61
Q

Clones

A

Genetically identical individuals

62
Q

Fertilisation

A

Fusion of gametes (haploid) to form zygote (diploid).

63
Q

Autosome

A

All other chromosomes except gametes, have homologues.

64
Q

Genome

A

Complete complement of organism’s chromosomes - carry genes.

65
Q

Synapsis

A

Pairing during prophase 1 which leads to crossing over.

CCEA AS Biology Unit 1 (14 decks)

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