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Biology A level > Topic 3-Glossary > Flashcards

Topic 3-Glossary Flashcards

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1
Q

Eukaryotes

A

Organisms whose cells contain their DNA inside a nucleus and have discrete membrane bound organelles.

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2
Q

Prokaryotes

A

Organisms whose cells do not contain their DNA within a nucleus, or other membrane bound cell organelles. The bacteria. Considered an earlier stage in the evolution of life than the eukaryotes.

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3
Q

Rough endoplasmic reticulum

A

Interconnected membrane-bound, flattened sacs found in the cytoplasm of eukaryotes, with ribosomes attached to the surface.

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4
Q

Smooth endoplasmic reticulum

A

As above but with no ribosomes attached, makes lipids and steroids.

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5
Q

Ribosomes

A

A small organelle composed of RNA and protein that is the site of protein synthesis

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6
Q

Mitochondria

A

Organelle with inner and outer membrane,inner membrane is folded to form cristae. Site of later stages of aerobic respiration.

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7
Q

Centrioles

A

A paired organelle that helps organise the microtubules in animal cells nuclear division. Hollow cylinders, formed by a ring of nine microtubules.

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8
Q

Lysosomes

A

Single membrane bound organelles which contain digestive enzymes. Involved in breakdown of unwanted cells/structures.

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9
Q

Nucleus

A

Double membrane bound organelle with several nuclear pores. Contain the chromosomes and the nucleolus.

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10
Q

Nucleolus

A

Dense body within the nucleus where the ribosomes are made.

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11
Q

Golgi apparatus

A

Flattened membrane bound sacs formed by fusion of vesicles from the ER. Plays a role in the production and release of secretory material e.g. digestive enzymes.

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12
Q

Protein trafficking

A

The process by which proteins are made to where they are needed, and/or secreted from the cell.

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13
Q

Peptidoglycan

A

Type of polysaccharide/polypeptide compound found in the prokaryotic cell wall.

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14
Q

Capsule

A

Slime layer surrounding the cell wall of some prokaryotes.

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15
Q

Pili

A

The protein tubes which allow bacteria to adhere to surfaces.

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16
Q

Flagellum

A

Rigid rotating helical-shaped tail like structure used for movement.

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17
Q

Gametes

A

The mature sexual reproductive cell, e.g. the egg or sperm.

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18
Q

Acrosome

A

Modified lysosome found at the forward tip of an animal sperm, contains enzymes which break down jelly-like coating of the ovum.

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19
Q

Fertilisation

A

Process where the gametes combine, and the nuclei fuse to form the zygote.

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20
Q

Zygote

A

Fertilised egg, in which the gamete nuclei are also fused. The earliest stage of the diploid generation.

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21
Q

Haploid

A

One copy of each chromosome, found in the gametes=n

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22
Q

Diploid

A

Two copies (homologise) of each chromosome =2n. Usually Aries as a result of the fusion of two gametes, each with just one copy of each chromosome.

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23
Q

Meiosis

A

Division of a diploid nucleus to produce four haploid daughter cells. The process consists of two successive divisions with only one cycle of chromosome replication.

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24
Q

Independent/random assortment

A

The random separation during meiosis of a non-homologous chromosomes; so that each homologous pair of chromosomes can pass independently of another homologous pair of chromosomes, into a gamete.

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25
Q

Crossing over

A

The breaking and random rejoining of chromatids during the first prophase of meiosis. It results in the arrangement of genetic material and is important source of genetic variation.

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26
Q

Chiasma/chiasmata

A

The visible manifestation of crossing over between homologous chromosomes. The point where the chromatids break and rejoin during the first prophase of meiosis.

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27
Q

Pollen tube

A

Tube formed from the germinating pollen grain when it lands in stigma. The tube grows down through the style.

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28
Q

Tube nucleus and generative

A

The pollen grain contains two nuclei.

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29
Q

Polar nuclei

A

The two polar nuclei in the embryo sac fuse with one of the male gametes to form a triploid cell. The triploid cell divides to form the endosperm.

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30
Q

Egg nucleus

A

One of the male gametes fuses with the egg nucleus to form the diploid zygote. The diploid zygote divides to form the embryo.

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31
Q

Radicle

A

Young root

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32
Q

Plumule

A

Young shoot

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33
Q

Cotyledons

A

Seed leaves- mono=1, di=2.

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34
Q

Endosperm

A

Storage tissue in the seed.

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35
Q

Testa

A

Seed coat

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36
Q

Fruit

A

Ovary will develop into this.

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37
Q

Mitosis

A

Cell division which produces two daughter cells each with a chromosome complement identical to that of the original cell.

38
Q

Cell cycle

A

The controlled series of events where one cell divides to produce and another cell identical to the parent cell. Includes all the stages of interphase and mitosis.

39
Q

Interphase

A

The period between successive nuclear divisions. Consists of the G1, S and G2 phases. Length of interphase may vary.

40
Q

G1 phase

A

First gap phase between the end of mitosis and the onset of the S phase, most variable in length.

41
Q

S phase

A

The stage of interphase during which DNA is replicated.

42
Q

G2

A

Second gap phase, between the S phase and mitosis.

43
Q

Prophase

A

The first stage of nuclear division during which the chromosomes become thicker and shorter to form chromatids, joined together by a centromere. The Spindle forms and the nuclear membrane breaks down.

44
Q

Metaphase

A

The stage of nuclear division at which the chromosomes line up in one plane. The Centromeres are attached to spindle fibres.

45
Q

Anaphase

A

The stage of nuclear division where the spindle fibres shorten, pulling chromatids to each pole. The spindle then breaks down.

46
Q

Telophase

A

The final stage of nuclear division where the chromosomes become diffuse and the nuclear membrane reforms.

47
Q

Chromatid

A

Each of a pair of sister chromosomes, from the time at which molecular duplication occurs until the time at which centromere separate at the anaphase of nuclear division.

48
Q

Chromosome

A

In eukaryotes, a long strand of DNA that contains part of the genetic information of cells, in the form of many genes.

49
Q

Centromere

A

The region where sister chromatids join.

50
Q

Chromatin

A

The nuclei can acid-protein complex found in eukaryotic chromosomes.

51
Q

Asexual reproduction

A

Reproduction without gametes

52
Q

Blastocyst

A

Hollow ball of cells surrounding a central cavity,formed five days after conception.

53
Q

Stem cells

A

Cells found in embryo, foetus and adult which can divide repeatedly throughout life and are unspecified. Given appropriate signals they can differentiate into many specialised cell types.

54
Q

Differentiation

A

The process by which cells become specialised in terms of biochemistry and/or morphology.

55
Q

Pluripotent

A

Can differentiate into most, but not all, of the 216 cell types.

56
Q

Totipotent

A

Cells can divide to form a complete human being.

57
Q

Multipotent

A

Can differentiate to form a small subset of cell types.

58
Q

Cloning

A

The process where the nucleus from one cell of an animal is transplanted into an un-fertilised egg (nucleus previously removed). The diploid cell will produce an organism genetically identical to the organism from which the nucleus was used.

59
Q

Therapeutic cloning

A

A procedure designed to provide cloned stem cells for a patient. The patient would donate diploid cells (e.g skin cells), the nucleus would be removed and inserted into an empty ovum producing a diploid cell (somatic cell nuclear transfer). This cell could be stimulated to divide to form blastocyst from which stem cells could be harvested.

60
Q

cDNA

A

Complimentary DNA made using an RNA template and the enzyme reverse transcriptase.

61
Q

Promoter

A

The region of DNA, upstream of the coding part of the gene, that acts as the initial biding site for the RNA polymerase.

62
Q

Gene induction

A

The process where transcription and translation of a gene occurs and a protein is produced. This is what we mean when we say a gene has been “switched on”.

63
Q

B-galactosidase

A

Enzyme found in bacteria which break down lactose to form glucose and galactose. Expression is normally prevented by a repress or binding to the operator sequence. Expression of this enzyme is induced when lactose is present.

64
Q

Regulator protein

A

A protein which attaches to RNA polymerase and a promoter region - required for transcription to be initiated.

65
Q

Repressor protein

A

Molecules (often proteins) which prevent transcription in a variety of ways, e.g. by binding to promoter region and blocking transcription.

66
Q

Signal Proteins

A

Can be hormones, growth factors or other regulatory molecules which switch on gene transcription.

67
Q

FOP- Fibrodysplasia ossificans progressiva

A

Rare condition where bone growth occurs in odd places. Caused by a mutation which means genes that cause bone growth are not switched off in white blood cells.

68
Q

Tissue

A

A group of specialised cells working together to carry out one function.

69
Q

Adhesion molecules

A

Cell surface recognition molecules which enable cells to recognise and attach to each other.

70
Q

Organ

A

A group of tissues working together to carry out one function.

71
Q

Master genes

A

Genes which switch on the expression of many other genes that control the development of large body segments.

72
Q

Meristem

A

Area of undifferentiated plant cells where cell division will form specialised plant organs.

73
Q

ABC genes

A

Three genes that determine which flowering structure will for from meristem.
Gene A expression results in a sepal formation.
Gene B expression results in carpel formation.
Gene A and B expression results in petal formation.
Gene B and C expression results in stamen formation.

74
Q

Genotype

A

Genetic makeup of an organism.

75
Q

Phenotype

A

The observable properties of an individual as they have developed under the combined influence of the genetic constitution of the individual and the effects of the environmental factors.

76
Q

Continuous variation

A

Characteristics which can be measured on a continuous scale, e.g. height

77
Q

Discontinuous variation

A

Discrete characteristics, e.g. male, female

78
Q

Polygenic

A

Number of genes involved in the inheritance of the same characteristics.

79
Q

Where several genetic and one or more environmental factors are involved the condition is said to be _____________________

A

Multifactorial

80
Q

Melanin

A

Dark pigment in the skin, protects DNA from UV damage.

81
Q

Melanin-stimulating hormone (MSH).

A

Hormone which induces gene expression in melanocytes to produce melanin. Binds to cell surface receptors.

82
Q

Melanosome

A

Melanin is packaged into these vesicles and transferred to nearby skin cells.

83
Q

Tyrosinase

A

Enzyme involved in the first step in the metabolic pathway that makes melanin, which changes tyrosinase to melanin. Albinos have mutated version of this enzyme.

84
Q

MAOA Monoamine oxidase A

A

Enzyme which catalyses the breakdown of a neurotransmitter in the brain involved in regulation of behaviour.

85
Q

Cancer

A

A disease caused when the rate of cell multiplication is faster than the rate of cell death of cell death.

86
Q

Tumour

A

A disorganised mass of cells, often growing out of control. If malignant, may spread to other parts of the body.

87
Q

Carcinogen

A

A substance that causes cancer.

88
Q

Oncogenes

A

Genes which code for proteins that stimulate the cell cycle, stimulating the transition from one stage to the next.

89
Q

Tumour suppressor genes

A

Genes which produce suppressor proteins that stop the cell cycle.

90
Q

p53

A

A tumour suppressor gene which inhibits the CDKs at the G1/S transition and therefore stops the cell cycle.

91
Q

BRCA1

A

A gene which normally produces a protein which repairs DNA. Mutated in some cases of breast cancer.

92
Q

BRCA2

A

A second breast cancer gene, found on chromosome 13, which has a DNA repair function.

Biology A level (12 decks)

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