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biology yr 12 > chapter 2 😎 > Flashcards

chapter 2 😎 Flashcards

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1
Q

allele

A

One of various versions of the same gene (at the same locus) distinguished by small differences in the DNA sequence

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2
Q

apoptosis

A

A programmed series of events that leads to cell death (as a result of the dismantling of the internal contents of the cell by various enzymes, including caspases)

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3
Q

asexual reproduction

A

The process by which a single parent produces offspring and that does not involve fusion of gametes; a process that usually results in identical offspring

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4
Q

autosome

A

A chromosome that is not a sex chromosome

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5
Q

binary fission

A

The division of a cell into two cells without mitosis; a prokaryotic cell undergoes binary fission to form two identical daughter cells; a form of asexual reproduction

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6
Q

bivalent

A

A structure (visible in a cell during prophase I of meiosis) made up of two homologous chromosomes joined together

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7
Q

cell cycle

A

An ordered sequence of events in the life of a cell from when it was formed from a parent cell until its own division

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8
Q

cell division

A

The splitting of a cell into two new functioning cells

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9
Q

cell plate

A

The structure produced by dividing plant cells in the place where the new cell wall is forming

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10
Q

centriole

A

A minute rod-shaped organelle present in many resting cells, just outside the nuclear membrane that helps make the spindle fibres for cell division; a centrosome contains two centrioles; it is usually absent in plants

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11
Q

centromere

A

The waist-like constriction in a chromosome where the spindle fibres attach; it enables the movement of chromosomes during cell division

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12
Q

centrosome

A

An organelle containing a pair of centrioles; it duplicates during cell division, while the DNA is duplicating, and the two centrosomes then separate to opposite poles of the dividing cell; it produces the spindle during cell mitosis and meiosis, and one of the centrosomes goes into each daughter cell

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13
Q

chromatid

A

Daughter strand of a duplicated chromosome that is joined to another chromatid by a centromere

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14
Q

chromatin

A

An organised, loosely coiled complex of DNA and its proteins that is found in eukaryotic non-dividing cells; it is more compact than the DNA of prokaryotes; chromatin supercoils to become the chromosomes observable during eukaryotic cell division

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15
Q

chromosome

A

A structure composed of DNA and protein that contains linear arrays of genes carrying genetic information; prokaryotes generally have one circular chromosome, whereas eukaryotes have a number of linear chromosomes

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16
Q

cleavage

A

The division of the cytoplasm in an animal cell

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17
Q

cleavage furrow

A

A shallow, ring-like depression that forms on the surface of an animal cell undergoing cytokinesis as contractile microfilaments pull the cell membrane inward; it defines where the cytoplasm will be divided to make two cells

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18
Q

crossing over

A

The exchange of genetic material between maternal and paternal homologous chromosomes (of non-sister chromatids) that occurs during the first step of meoisis (prophase I)

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19
Q

cytokinesis

A

The division of the cytoplasm immediately after mitosis, meiosis I or meiosis II to create two separate daughter cells

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20
Q

differentiation

A

The process during development whereby newly formed cells become more specialised as they mature; an example of cell differentiation is the development of root tip cells of plants into phloem, xylem and root hairs; during the process of differentiation, cells gain specialised structures and functions

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21
Q

Diploid (2n)

A

Describes a cell or organism that has a genome that contains two copies of each chromosome; the diploid number of chromosomes is represented by 2n

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22
Q

DNA (deoxyribonucleic acid)

A

The information-containing molecule present in all living things that contains the instructions, written in a chemical code, for the production of proteins by the cell; the information it contains is sufficient for the making and maintaining of the organism; in addition, DNA is the genetic material that passes this information on to the next generation

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23
Q

Eukaryotic cell

A

A complex cell containing membrane-bound organelles,including a nucleus

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24
Q

Fertilisation

A

The fusion of haploid male and female gametes during sexual reproduction to produce a diploid zygote; the random union of gametes is known as random fertilisation

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25
Q

gametes

A

A male or female reproductive cell; one of each type combine at fertilisation; in humans, the gametes are ova and sperm cells; in flowering plants, pollen grains contain male gametes and ovules contain female gametes

26
Q

gene

A

A unit of heredity that transmits information from one generation to the next; a segment of DNA that codes for a polypeptide

27
Q

genetic

A

Refers to the mechanisms and patterns of inheritance; relating to the transmission of coded chemical instructions from one generation to the next

28
Q

genome

A

All of the genetic material contained in an organism or a cell; it includes the chromosomes within the nucleus and the DNA in mitochondria and chloroplasts

29
Q

Germline cell

A

A specialised sex cell that gives rise to gametes; early in an embyro’s development, its germline cells specialise into male or female germ cells

30
Q

Haploid (n)

A

Describes a cell or organism that has a genome that contains one copy of each chromosome; the haploid number of chromosomes is represented by n

31
Q

Heredity

A

The study of inheritance; the genetic transmission of characteristics from one generation to another

32
Q

Heterosome

A

One of the non-identical chromosomes that pairs up at meiosis (e.g. the X and Y chromosomes in male humans)

33
Q

histone

A

A protein around which DNA winds in eukaryotic cells to form a nucleosome

34
Q

Homologous chromosomes

A

A pair of chromosomes of the same size and shape and that has the same genes at the same locations

35
Q

Interphase

A

The stage between nuclear divisions that involves metabolic activity, growth, and duplication of chromosomes

36
Q

Karyotype

A

A display of the number and appearance of the chromosomes of an organism or cell as observed at metaphase

37
Q

Locus (plural loci)

A

The position a gene occupies on a chromosome

38
Q

Maternal chromosome

A

The chromosome in a pair of chromosomes that came from the mother

39
Q

meiosis

A

A type of cellular division in sexually reproducing organisms that involves two rounds of cell division, but only one round of DNA replication; during meiosis, the chromosome number of a cell is halved so that the daughter cells are haploid; meiosis is the basis of gamete formation in some plants and animals and of spore formation in other plants

40
Q

mitosis

A

A type of nuclear division in somatic cells that maintains the parental diploid number of chromosomes in the daughter cells; it is the basis of bodily growth and of asexual reproduction in many eukaryotic species

41
Q

Nitrogenous base

A

A structural component of the nucleotides that make up DNA or RNA

42
Q

Nucleoid

A

The region within a prokaryotic cell that contains the genetic material

43
Q

Nucleolus

A

A structure found within the nucleus of a non-dividing cell; a site in which ribosomes are made from protein and RNA subunits

44
Q

Nucleotide

A

The basic building block of nucleic acids (DNA and RNA); nucleotides are linked together by phosphodiester bonds; each nucleotide is made up of a five-carbon sugar, a phosphate group and a nitrogenous base

45
Q

Nucleus

A

The dense organelle of a eukaryotic cell that contains genetic material in the form of chromosomes and is enclosed by a nuclear membrane; in its resting phase, the genetic material takes the form of loosely coiled chromatin; the chromatin supercoils and condenses to form chromosomes before cell division

46
Q

organelle

A

A specialised part of a cell that has its own specific function; a ‘little organ’

47
Q

Paternal chromosome

A

The chromosome in a pair of chromosomes that came from the father

48
Q

Plasmid

A

A small circular piece of DNA, found in bacteria, that is able to replicate independently of the cell’s chromosomes; engineered plasmids may carry antibiotic-resistance markers

49
Q

prokaryote

A

A single-celled organism that lacks membrane-bound organelles such as a nucleus

50
Q

sex chromosome

A

A chromosome that determines the sex of an organism and affects sexual traits

51
Q

Sexual reproduction

A

A form of reproduction in which offspring are produced from two parents by the fusion of male and female gametes

52
Q

somatic cell

A

A body cell that is not a germ cell

53
Q

synapsis

A

Synapsis The pairing of homologous chromosomes during prophase I of meiosis

54
Q

synapsis

A

The pairing of homologous chromosomes during prophase I of meiosis

55
Q

trait

A

An inheritable characteristic; phenotype

56
Q

zygote

A

The first cell of a new individual; it is formed by fusion of a male and a female gamete (fertilisation) during sexual reproduction

57
Q

why do Chromatin Condenses to Form Chromosomes

A

Chromatin (the loose, thread-like form of DNA) condenses to form tightly coiled chromosomes to make the genetic material more manageable. Condensed chromosomes are easier to move and separate without breaking during cell division, ensuring each new cell will get a full set of DNA.

58
Q

why
Nuclear Membrane Disintegrates and Nucleolus Disappears

A

The nuclear membrane and nucleolus (which makes ribosomes) break down to give spindle fibers access to the chromosomes. The nuclear membrane acts as a barrier, so disintegration allows chromosomes to interact with the spindle fibers and enables their distribution to daughter cells.

59
Q

why
Mitotic Spindle Begins to Form

A

The mitotic spindle is a structure made of microtubules that helps to organize and sort chromosomes during division. It forms to guide chromosomes to the correct locations within the cell, ensuring each daughter cell receives the right set of chromosomes. This step is crucial for accurate cell division and preventing genetic abnormalities.

60
Q

why
Centrosomes (Each Containing Two Centrioles) Move Toward Opposite Poles of the Cell

A

Centrosomes act as the main microtubule-organizing centers. Moving to opposite poles allows the mitotic spindle to form between them, creating the structure that will guide and pull chromosomes apart. Positioning the centrosomes on opposite sides ensures that the spindle fibers can equally divide chromosomes to both new cells.

biology yr 12 (3 decks)

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