Chapter 16: Inherited Change Flashcards Preview

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Flashcards in Chapter 16: Inherited Change Deck (40):
1

How many PAIRS of matching chromosomes do humans have?

22

2

what is the definition of 'homologous'?

similar in structure and composition

3

what are the non-matching chromosomes in humans?

the sex chromosomes

4

name the two types of chromosomes

sex chromosomes
autosomes (all the other chromosomes)

5

each chromosome has a characteristic set of ... which code for different features

genes

6

what is the locus?

the position on the chromosome where genes for particular characteristics are always found

7

definition of a homologous chromosome

pair of chromosomes in a diploid cell that have the same structure as each other, with the same genes at the same loci, and that pair together to form a bivalent during the first division of meiosis

8

definition of a gene

a length of DNA that codes for a particular protein or polypeptide

9

definition of an allele

a particular variety of a gene

10

definition of a locus

the position at which a particular gene is found on a particular chromosome; the same gene is always found a the same locus

11

name the two types of nuclear division

growth and sexual reproduction

12

what type of nuclear division is growth?

mitosis

13

what type of division is sexual reproduction?

meiosis

14

define 'haploid'

a cell which contains only one complete set of chromosomes

15

events in middle prophase 1

-homologous chromosomes pair up (synapsis)
-each pair is a bivalent
-centrosomes move to opposite ends of the nucleus

16

events in metaphase 1

-bivalents line up across equator of spindle, attatched by centromeres

17

events in late prophase 1

-nuclear envelope breaks up as in mitosis
-crossing over of chromatids may occur
-nucleolus 'disappears'
-spindle forms

18

events in metaphase 1

-bivalents line up across equator of the spindle, attached by centromeres

19

events in anaphase 1

-centromeres do not divide
-whole chromosomes move towards opposite ends of the spindle, centromeres first, pulled by microtubules

20

events in telophase 1

-nuclear envelope re-forms
-nucleolus re-forns
cytokinesis
-chromosomes reach poles of spindle

21

events in prophase 2

-nuclear envelope and nucleolus disperse
-centrosomes and centrioles replicate and move to opposite poles of the cell

22

events in metaphase 2

chromosomes line up separately across equator of spindle

23

events in anaphase 2

-centromeres divide
-spindle microtubules pull the chromatids to opposite poles

24

events in telophase 2

four haploid daughter cells are formed

25

define 'spermatogenesis'

the formation of male gametes

26

define 'oogenesis'

the formation of female gametes

27

define 'genotype'

the alleles possessed by an organism

28

define 'homozygous'

having two identical alleles of a gene

29

define 'heterozygous'

having two different alleles of a gene

30

what is an 'allele?'

different varieties of the same gene

31

define 'phenotype'

its characteristics, often resulting from an interaction between its genotype and its environment

32

define 'dominant allele'

one whose effect on the phenotype of a heterozygote is identical to its effect in a homozygote

33

define 'recessive allele'

one that is only expressed when no dominant allele is present

34

define 'codominant alleles'

where both alleles have an effect on the phenotype of a heterozygous organism

35

define 'F1 generation'

the offspring resulting from a cross between an organism with a homozygous dominant genotype, and one with a homozygous recessive genotyope

36

define 'F2 generation'

the offspring resulting from a cross between two F1 (heterozygous) organisms

37

define 'test cross'

a genetic cross in which an organism showing a characteristic caused by a dominant allele is crossed with an organism that is homozygous recessive; the phenotypes of the offspring can consequently be a guide to whether the first organism is homozygous or heterozygous

38

define 'linkage'

the presence of two genes that are on the same chromosome, so that they tend to be inherited together and do not assort independently

39

define 'gene mutation'

a change in the structure of a DNA molecule, producing a different allele of a gene

40

what is a 'silent mutation'

a mutation that has no apparent effect on an organism