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Biology Paper 1 > Genetics > Flashcards

Genetics Flashcards

1
Q

what are advantages of asexual reproduction?

A

+ can produce offspring really quickly-> colonise an area
+ only need one parent -> reproduce whenever confirms are favourable and less energy & time spent

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2
Q

what are disadvantages of asexual reproduction

A
  • no genetic variation > whole population will be affected if disease occurs& reduces ability to adapt to new environmental conditions
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3
Q

what are advantages of sexual reproduction

A
  • genetic variation > have characteristics that help them survive in environmental changes
  • can use selective breeding > organisms with desirable traits can be produced
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4
Q

what are disadvantages of sexual production

A
  • two parents are required > diffusion to reproduce in endangered species or those who live solitary lifestyles
  • more energy and time needed > fewer offspring are produced
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5
Q

what is sexual reproduction?

A

gametes from each parent fuse during fertilisation to for a. diploid zygote which undergoes cell division to become an embryo

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6
Q

what are gametes

A
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7
Q

what is asexual reproduction.

A

reproduction where cells divide by mitosis to form two genetically identical diploid cells known as daughter cells

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8
Q

What is the first stage of meiosis?

A
  1. interphase - duplicate dna so one arm of each x chromosome is exact copy. 1/2 chromosomes are from the father and the other is from mother
  2. first cell division > chromosomes line up in the middle
  3. pairs of chromosomes are separated and move to the opposite sides of the cell > each cell has a copy one each chromosome
  4. each cell has a mixture of parent chromosomes > genetical variation
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9
Q

what happens during the second stage of meosis

A
  1. chris omes lime uo in the middle then are pulled apart to opposite sides of cell
    2.four unique haploid cells are productsd > each gamete is genetically different
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10
Q

why is meosis important for sexual reproduction?

A
  • increases genetic variation
  • ensures resultant zygote is diploid
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11
Q

what are similarities of mitosis and meosis?

A
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12
Q

what are differences between mitosis and meosis?

A
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13
Q

describe what dna is.

A

polymer of nucleotides made of two strands coiled to form a double helix
- strands are linked by series of complementary base pairs joined together by weak hydrogen bonds

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14
Q

what do nucleotides consist of?

A

sugar and phosphate groups alternating to form a backbone with one of the four bases (A > t, c>G) attached to the sugar

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15
Q

what’s a chromosome?

A

ling coiled up molecules of dna

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16
Q

gene

A

section of dna on chromosome that codes for particular protein

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17
Q

what’s a genome?

A

all of organisms genetic material /dna

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18
Q

How can you extract dna from a fruit?

A
  1. Grind fruit tissues > break cell wall so DNA is released
  2. add saline solution > neutralise DNA charge and becomes less soluble
  3. add detergent > breaks down lipids of cell membrane surrounded DNA
  4. filter mixture to separate froth and insoluble bits
  5. add protease enzyme > catalyse breakdown o
  6. add ice cold ethanol > form precipitate so white strands of dna are left
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19
Q

explain how a gene codes for a protein

A
  • a sequence of three bases in a gene forms a triplet
  • each triplet codes for an amino acids
  • order of amino acid determines the structure ( how they fold) to produce specially shaped proteins & function
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20
Q

why is folding of amino acids important in proteins such and enzymes?

A

it determines the shape of the active site which is highly specific to the shape of the substrate

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21
Q

what is protein synthesis?

A

formation of protein from a gene

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22
Q

why is mRNA used in translation rather than DNA?

A

DNA contains genetic coding for protein but cannot move as nucleus is too big so it cannot reach the ribosome

23
Q

what is the process in transcription?

A

RNA polymerase binds to non coding region of DNA
2. RNA polymerase breaks the hydrogen bonds and separates the two DNA and moves along the strands
3. it uses coding DNA to produce a complementary mENA strand
4. once made, mRNA escapes nucleus to the cytoplasm through nuclear pores and attaches to fo the ribosomes

24
Q

describe the process of translation

A
  1. at the ribosome, the bases on mRNA are read in triplets (codons) for specific amino acids (so they match)
  2. the amino acids are carried by the tRNA to the ribosomes
    3 amino acids link together to for, polypeptide chains ( proteins)
25
Q

explain how tRNA is adapted to its function

A

they have anticodons which are complementary to the codons of the amino acids so they have the correct order when brought to the ribosomes

26
Q

define what genetic variation is

A

small change in order of bases that makes strands of dna different versions of the gene > may change protein shape & acitivit

27
Q

what’s mutation?

A

random change in base sequence of DNA which results in genetic variants

28
Q

Describe the effect of genetic variation / gene mutation in the CODING region of the DN

A

alters the amino acid sequence > alters final structure of protein & function can change

29
Q

How do mutations change sequences in bases?

A
  1. base is inserted into code > changes way its read > may change all amino acids code
  2. base is deleted from code > may change all amino acids coded
  3. base is subtitled > change one amino acids in sequence or not
30
Q

describe effects of genetic variation in the NON coding region of the dna

A

it affects the ability of how well RNA polymerase binds to the non coding region
this affects how much mRNA is transcribed > affects how much protein is produced > phenotype may be affected

31
Q

outline how the work of mendel helped scientists develop their understanding of generics

A
  • studied inheritance of different phenotypes of pea plants
  • esyabilishdd correlation between parent & off spring phenotypes
    -noted inheritance was determined by units passed onto descendants.
    decided
32
Q

what are mendel’s 3 conclusions?

A
  • characterises in offspring are determined by hereditary units
  • one unit from each parent
    -units can be dominant or ressessive
33
Q

what are alleles?

A

different versions of genes

34
Q

define genotype

A

combination of alleles

35
Q

describe phenotype

A

physical characteristics of an indivisible

36
Q

define homozygous

A

having inherited alleles that are the same (identical allleles of a gene)

37
Q

define heterozygous

A

having two different alles of a gene

38
Q

what’s the difference between do,inwant and recessive alleles?

A

dominant is expressed with capital letters and only 1 is needed whereas ressessive is expressed with small letters and needs 2 of its alleles

39
Q

define mono hybrid inheritance.

A

inheritance of a single gene

40
Q

what’s the problem with a single gene crosses?

A

mld characteristics are controlled by multiple alles rather than just ine

41
Q

WHAT are sex chromosome?

A

males have x and y chromosomes
women have two X cheoaomomss which allow them to develop
- egg cell always cries an x chromosome but speed can carry x or y > determines sex of embryo

42
Q

what are two ways mono hybrid inheritance can be represented?

A

1 punnet square
2. family pedigrees

43
Q

what’s a sex linked characteristics

A

characteristic that is coded by an allele found on a sex chromosome

44
Q

why are majority of the gene found on X chromosomes rather than Y chromsome

A

X chromosome is bigger so it carries majority of the genes

45
Q

why are men more like
y to show phenotype of recessive sex linked trait than women

A
  • women have two alleles for each sex linked gene
    -men have one allele so one
    recessive allele is required to produce recessive phenotype
46
Q

give an example of a characteristic that is determined by more than one allele

A

blood group

47
Q

what are the 4 blood groups

A

A,B, AB, O

48
Q

what are codominant alleles?

A

alleles that contribute to an organisms phenotype that are expressed equally

49
Q

describe codominance in blood groups

A

IÂ and I^b

50
Q

what is genetic varation

A

variations of genptypes of organisms in the same species due to the presence of different alleles
- new combinations of alleles may interact with each other to form new phenotypes
-

51
Q

what causes genetic variation with in a species?

A
  • random mutation
  • neutral mutation does not affect phenotype largely
  • sexual reproduction > alleles are combined in different ways
52
Q

what is environmental variation?

A

characteristics individuals acquire over a lifetime

53
Q

How can the genome project be applied to medicine?

A

PREDICTION AND PREVENTION OF DISEASES
- many diseases are caused by interaction of different genes
- to get an imrpoved unsertsanding of what gene causes what disease individuals can get tailored advice

Biology Paper 1 (5 decks)

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