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biology > story of us - part 1 > Flashcards

story of us - part 1 Flashcards

(60 cards)

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1
Q

name the bases

A
  • adenine
  • thymine
  • cytosine
  • guanine
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2
Q

what is a gene

A

a short section of DNA that codes for a particular protein

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3
Q

what is a genome

A

the entire DNA of an organism

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4
Q

where is genetic information found

A

nucleus

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5
Q

describe the structure of DNA

A
  • 2 strands (double stranded)
  • complimentary base pairing
  • made of nucleotides (polynucleotide)
  • double helix
  • sugar-phosphate backbone
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6
Q

how many chromosomes are there in all human body cells (except gametes), and how are they arranged

A

46, arranged in 23 pairs

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7
Q

how many chromosomes are there in human gametes

A

23

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8
Q

in humans, of the 23 pairs, what are 22 of the pairs called

A

autosomes

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9
Q

what are the 23rd pair of chromosomes called

A

sex chromosomes

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10
Q

what are pairs of matching chromosomes called

A

homologous pairs

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11
Q

what is an allele

A

an alternate form of a gene

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12
Q

what is a chromosome

A

made of DNA, genes located on, found in the nucleus

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13
Q

diploid definition

A

number of chromosomes found in body cells

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14
Q

haploid definition

A

number of chromosomes found in gametes

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15
Q

dominant definition

A

different forms of the same gene

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16
Q

recessive definition

A

allele that is not expressed in phenotype when dominant allele is present

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17
Q

codominance definition

A

both alleles are expressed in the phenotype

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18
Q

what does adenine always pair with

A

thymine

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19
Q

what does cytosine always pair with

A

guanine

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20
Q

variation definition

A

differences between individuals of the same species

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21
Q

what are the 3 causes of variation in humans

A

environmental, genetic, a combination of both

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22
Q

phenotypic variation definition

A

variability in the phenotype that exists in a population because of genetic variation and environmental factors

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23
Q

discontinuous variation:

A
  • usually caused by genetic variation alone
  • where there are distinct differences for characteristics
  • for example, blood group or eye colour
  • display data using bar chart
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24
Q

continuous variation:

A
  • often vary because of a combination of genetic and environmental causes
  • when there are very small degrees of difference for a characteristic
  • for example, height, mass, intelligence
  • display data using a histogram with a normal distribution curve - usually gives a smooth bell curve because of the small degrees of differences
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25
what are phenotypic features
observable + measurable characteristics of an individual that can be affectedly environmental factors + genetics
26
homozygous definition and example
same alleles e.g. bb
27
heterozygous definition and example
different alleles e.g. Bb
28
polygenic inheritance definition
many characteristics controlled by two or more genes working together
29
what does a pedigree diagram show
the family history of a genetic condition
30
what is the role of the nucleus
to control the activities of the cell, using genes
31
where is genetic information ‘stored’
on chromosomes
32
what do chromosomes consist of
a long section of DNA held in place by structural proteins (called histones)
33
what is DNA composed of
small sections called genes
34
what are the male chromosomes
XY
35
what are the female chromosomes
XX
36
what are pairs of matching chromosomes called
homologous pairs
37
what do homologous pairs carry
genes of the same features these genes are arranged in the same positions and sequence along the chromosome
38
what are cells with chromosomes arranged in homologous pairs called
diploid cells
39
what does the genetic code in the DNA determine
which proteins are built by the cell
40
how does DNA replicate
mitosis
41
what do genes do
instruct cells to produce a particular protein which leads to the development of features
42
what do individual nucleotides join together to form
a polynucleotide
43
in complementary base pairing how are the amounts of each A / T / C / G distributed
the amounts of A and T are always equal the amounts of C and G are always equal
44
what causes phenotypic variation
genetic - controlled entirely by genes environmental - caused entirely by the environment in which the organism lives
45
genetic variation:
- meiosis creates genetic variation between the gametes produced by an individual - this means each gamete carries substantially different alleles - during fertilisation, any male gamete can fuse with any female gamete to form a zygote - this random fusion of gametes at fertilisation creates genetic variation between zygotes as each will have a unique combination of alleles
46
examples of genetic variation in humans
- presence of earlobes - blood group - ability to roll tongue - eye colour gender
47
environmental variation
- characteristics of all species can be affected by environmental factors - ‘environmental’ simply means ‘outside of the organism’ so can include factors like climate, diet, culture, lifestyle and accidents during lifetime
48
examples of environmental variation
- accidents (leads to scarring) - eating too much + not exercising will cause weight gain
49
properties of continuous variation
describes characteristics that can change over a range of values
50
properties of discontinuous variation
either you have this characteristic or you don’t
51
examples of continuous variation
height, mass, intelligence
52
examples of discontinuous variation
blood group, eye colour
53
continuous variation graph
smooth bell shaped curve
54
discontinuous variation graph
bar chart, steep
55
what is continuous variation caused by
both genetic and environmental factors
56
what is discontinuous variation controlled by
genetic factors only
57
what are phenotypic features
observable and measurable characteristics of an individual that can be affected by environmental factors and genetics
58
what is polygenic inheritance
characteristics that are controlled by more than one gene
59
what do chromosomes in a homozygous pair contain
the same type of genes that code for the same characteristics, such as eye colour each chromosome in the pair, however, may have a different version of the gene
60
example of polygenic inheritance
skin colour -> the amount of melanin in the skin is controlled by many genes -> each gene has alleles that promote melanin production and alleles which do not -> this produces a wide range of phenotypes

biology (28 decks)

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