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Gcse Biology > B5.1 - Inheritance > Flashcards

B5.1 - Inheritance Flashcards

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1
Q

Phenotype

A

Appearance of an organism

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2
Q

Variation

A

Differences within a species

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3
Q

Two type/causes of variation:

A
  • genetic variation (genetic material inherited from parents)
  • environmental variation (environment in which you live in)
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4
Q

Characteristics causes by genetic variation:

A
  • eye colour
  • blood group
  • genetic disorders

(Caused by genes)

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5
Q

Characteristics caused by environmental & genetic variation

A
  • height

- weight

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6
Q

Characteristics caused by environmental variation

A
  • intelligence
  • language spoken
  • good swimmer
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7
Q

Discontinuous variation

A
  • characteristics fall into distinct groups
  • genetic variation
  • controlled by 1/2 genes
  • display in bar chart

(Eg. Gender, eye colour, blood type)

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8
Q

Continuous variation

A
  • takes any value in a range
  • genetic & environmental variation
  • controlled by multiple genes
  • display in histogram

(Eg. Leaf surface area, skin colour)

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9
Q

Asexual reproduction

A
  • requires only 1 parent
  • replicate their genetic material and divide by mitosis
  • no mixing of genetic material
  • each new organism genetically identical to parent cell (clone)
    Eg. Bacteria
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10
Q

What organisms can reproduce asexually

A
  • potato plants
  • spider plants
  • daffodils
  • sea anemones
  • star fish
  • bacteria
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11
Q

Sexual reproduction

A
  • requires 2 parents
  • offspring not identical as genetically information taken from both parents
  • results in variation (unique genome)
    Eg. Most animals/plants
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12
Q

describe sexual reproduction in animals

A
  • organisms produce sex cells = gametes (male: sperm, female: ova)
  • gametes fuse together in fertilisation
  • fertilised egg develops into offspring
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13
Q

Describe sexual reproduction in plants

A
  • pollen cell (male sex cell) fuses with egg cell (female sex cell) in ovule
  • to create new seed, will grow into plant
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14
Q

Advantages of asexual reproduction

A
  • if parent well adapted to area,m offspring will share identical characteristics
  • only 1 parent needed (animals don’t need to find partner, plants don’t require pollination) = faster reproduction
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15
Q

Disadvantages of asexual reproduction

A
  • adverse changes to biotic/abiotic factors may destroy species, all organisms will be affected as no variation
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16
Q

Advantages of sexual reproduction

A
  • variation in offspring leads to adaptations in species, some organisms contain adaptations required to cope with environmental pressure, can reproduce so population of species can continue
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17
Q

Disadvantages of sexual reproduction

A
  • requires 2 parents = slower reproduction so few offspring produced
18
Q

Diploid cells

A
  • Normal body cells
  • contain 2 sets of each chromosome
  • contain 46 chromosomes
19
Q

Haploid cells

A
  • eg. Ova & sperm cells
  • have 1 of each chromosome
  • contain 23 chromosomes
20
Q

What happens during fertilisation

A
  • 2 haploid gamete cells join together forming a diploid cell (zygote)
  • zygote divides many times by mitosis to produce new organism
  • unique combination of genes in new organism as mixture of parents genetic material
21
Q

Genome

A

All genetic material present in an organism

22
Q

How are gametes produced

A
  • By meiosis (type of cell division)
  • 4 haploid cells produced from 1 diploid parent cell
  • occurs in ovaries to produce ova & testes to produce sperm
23
Q

First stage of meiosis

A
  • chromosomes in diploid cells copied
  • chromosomes line up along middle of cell in pairs
  • members of each pair pulled to opposite ends of cell (sections of DNA swapped)
  • cell divides in two
  • two separate cells formed
24
Q

Second stage of meiosis:

A
  • chromosomes line up along middle of each of 2 new cells
  • each chromosome pulled in half
  • single copy of each chromosome goes to opposite ends of cell
  • each cell divides in two
  • four new haploid cells made, each genetically different from each other & parent cell
25
Q

Alleles

A

Different forms of a gene

26
Q

Dominant allele (B)

A

Version of a gene whose characteristics is always expressed if present in genome, only 1 copy needed

27
Q

Recessive allele (b)

A

Version of a gene whose characteristic only expressed if 2 copes are present in genotype

28
Q

Genotype

A

Combination of alleles present in an organism

29
Q

3 types of genotypes

A
  • homozygous dominant (BB)
  • homozygous recessive (bb)
  • heterozygous (Bb)
30
Q

How did Gregor Mendel discover how characteristics are inherited

A
  • carried out experiments using pea plants
  • pea plants can produce pods that are green/yellow
  • green = dominant, yellow = recessive
31
Q

Why does the father determine the sex of its offspring

A

Male gametes can have either an X or Y chromosome whereas all female gametes contain an X chromosome

23rd pair of chromosomes = sex chromosomes:
Female = XX
Male = XY

32
Q

Mutation

A

When the sequence of DNA bases is altered

33
Q

Genetic variant

A
  • Different version of an allele, caused by change in DNA

- all arise from mutations

34
Q

What determines the effect the mutation will have on an organism

A

The position of the mutation in the DNA sequence

35
Q

What affects do mutations have on an organism

A
  • most mutations won’t affect organism’s phenotype
  • some mutations may influence organisms phenotype
  • few mutations will determine organism’s phenotype, lead to variation within a species
36
Q

Harmful mutations cause:

A
  • cancer (cells grow & divide uncontrollably)
  • production of abnormal protein channels (allow molecules to transport through cell membrane) that don’t function properly (eg. cystic fibrosis)
  • different shaped protein molecules (eg. sickle cell anaemia = unusually shaped haemoglobin molecules, blood cells sickle shaped)
37
Q

Give an example of a neutral mutation (no benefit or harm)

A

Ability to roll your tongue

38
Q

Give an example of a beneficial mutation

A

Mutations in some bacteria enable them to be resistant to antibiotics, increases chance of survival

39
Q

How can mutations alter an organism’s phenotype, what can this lead to

A
  • in gene, DNA bases may be changed, added, deleted = changes sequence of bases
  • order of bases in mRNA (transcription) different = different order of amino acids = wrong protein produced / fold incorrectly
  • if mutation occurs in non-coding section of DNA (triggers process of transcription), gene may not be transcribed into mRNA = proteins won’t be produced
40
Q

What may happen as a result of the proteins not being produced properly due to mutations

A
  • if protein is an enzyme, active site may change shape
  • can no longer bing to substrate & catalyse specific chemical reactions
  • results in metabolic diseases
    (eg. phenylketonuria, PKU = phenylalanine can’t be broken down by body = brain damage)
41
Q

Give the years & stages of the history of genetics

A

1866: Discovery that certain characteristics are inherited
1869: Nuclein discovered
1944: Genes can be transferred from 1 generation to next
1950: DNA base pairs discovered
1952: DNA crystals photographed
1953: Double-helix structure of DNA identified
1953-2000: Advances in genetics
2003: Human genome project complete

42
Q

Describe Gregor Mendel discoveries in 1866

A

Carried out experiments on peas, noticed that:

  • characteristics in plants were determined by hereditary units (now called genes)
  • hereditary units are passed on from both parents, 1 unit from each
  • hereditary units are dominant or recessive

Gcse Biology (15 decks)

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