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Biology > B5 - Genes, Inheritance and selection > Flashcards

B5 - Genes, Inheritance and selection Flashcards

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1
Q 
Definitions of:
Genome 
Chromosomes 
Gene 
Alleles
A

Genome: all the genetic material of an organism

Chromosomes: Long coiled up molecule of DNA which humans have 23 pairs (46 in total) and contains many genes

Gene: a short section of DNA that codes for a protein

Alleles: Different variations of the same gene

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2
Q

Genotype vs phenotype:

A

Genotype: All the genes and alleles an organism has

Phenotype: the gene that the organism displays -> the characteristic expressed

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3
Q

Mutations in coding DNA vs non coding DNA?

A

Mutations in coding DNA:
- affects the protein coded for by the gene

Mutations in Non-coding DNA:
- affects how genes are expressed - whether or not the gene is ‘switched on’

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4
Q

Difference between mitosis and meiosis?

A

MITOSIS:

  • Occurs all over the body for growth and repair - replacing cells that need replacing and makes new cells
  • 1 division event
  • Produces genetically identical cells (produces diploids)
  • fertilised egg (zygote) undergoes mitosis into an embryo

46 chromosome original cell -> splits into two cells with 46 chromosomes (diploid)

MEIOSIS:

  • Only for gamete (sex cell - sperm and egg) production
  • 2 division event
  • Produces cells which are not genetically identical (produces haploids)

46 chromosome original cell -> splits into two cells with 46 chromosomes (diploid) -> the two diploid cells split again into cells with 23 chromosomes (haploid cells)

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5
Q

Steps to meiosis:

A

1) Before cell divides, it duplicates its DNA
2) In the first division, the chromosomes line up in pairs in the centre of the cell and are pulled apart
3) Mixing; chromosomes from the father and mother mix creating variation
4) Chromosomes pull to opposite ends of the cell and cell divides
5) Genetically different gamete cells with 23 chromosomes formed

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6
Q

Advantages and disadvantages of asexual reproduction and sexual reproduction?

A

ASEXUAL REPRODUCTION:
Advantages:
- Can produce offspring very quickly
- One parent is needed - reproduce when conditions favor them
Disadvantages:
- No genetic variation, if the environmental conditions change, the whole population will be affected

SEXUAL REPRODUCTION:
Advantages:
- Creates genetic variation between offspring, so if the environmental conditions change, it is more likely that some individuals can survive, leads to evolution and better adapted species
Disadvantage:
- Takes more time and energy so organisms produce less offspring in their lifetime
- Two parents are need for reproduction

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7
Q 
Definitions of
Dominant allele 
Recessive allele 
Homozygous 
Heterozygous
A

Dominant allele: Only one allele is needed for characteristic to be expressed

Recessive allele: Two alleles are needed for characteristic to be expressed

Homozygous: If you have two alleles the same for that particular gene eg. (BB)

Heterozygous: If you have two different alleles for that particular gene eg. (Bb)

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8
Q

Plummet squares

A
  • Predict the probability of the offspring obtaining a characteristic

How to draw it?

1) Draw 4 squares
2) Outside the squares label the parents genotype
3) Pair up the parents genes and fill in the 4 square

DRAW IT

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9
Q

What is artificial classification?

A

A classification system only reliant on observable features to place organism into groups - such as whether they lay eggs or fly

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10
Q

What is natural classification?

A

Is a method of classification based on evolutionary relationships

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11
Q

What is the 5 kingdoms?

A 
Plants 
Animals 
Fungi 
Protists 
Prokaryotes
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12
Q

What is the Hierarchical classification system?

A

Kids Prefer Candy Over Fancy Green Salads

Kingdom 
Phylum 
Class 
Order 
Family 
Genus 
Species
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13
Q

How to form a binomial name?

A

Binomial name = Genus + species

Genus = capital
Species = lower case

E.G: Genus = lemur
Species = catta

Binomial name = Lemur catta

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14
Q

Species definition?

A

A group of organism that can breed with each other to produce fertile offspring

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15
Q

What is phylogenetics?

A
  • a diagram which shows evolutionary relationships
  • the branches on a phylogeny show a common ancestor
  • species which are closer together are more closely related
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16
Q

Definition of:
Adaptation
Evolution

A

Adaptation: characteristics which enable survival and makes an organism suited to its habitat

Evolution: The gradual change in inherited characteristics of a population over time through the process of natural selection

17
Q

3 ways a genetic variation is created in a population?

A

1) Mutation: spontaneous and natural change in sequence of bases in DNA.
2) Sexual reproduction: Two organism are required to produce an offspring. This produces new variations of genes
3) Meiosis: Produces genetically different gametes. All gametes are different to each other creating new variation of genes

18
Q

Evolutionary sequence?

A

1) A population of organisms show variations. Not all organism are the same
2) Environmental changes
3) Some of the organism die and those with the best adaptations survive
4) The survivors are more likely to reproduce and pass on their genes
5) Their offspring inherit their characteristics which help them better survive

19
Q

What scientist discovered the natural selection theory?

A

Darwin discovered the theory - he proposed that organisms adapt over generations

Lamarck - believed that characteristics can be adapted in a lifetime

20
Q

Why might extinction occur?

A
  • New disease
  • New predators
  • More successful competitors
  • Changes to the environment over geological time - like climate change
  • A single catastrophic event - like an asteroid

Extinction occurs when there is a change in the environment which is too large or rapid for species to adapt

21
Q

What is the evidence for evolution?

A

Fossils

  • The deeper the rock containing a fossil, the older the fossil
  • We can use this to chronological order fossil and changes in characteristics over time
22
Q

how does bacteria become antimicrobial?

A

1) Bacteria has variation - some bacteria has an antimicrobial gene and some don’t
2) You take the antimicrobial drug
3) Bacteria without the antimicrobial gene are killed while the bacteria with the antimicrobial gene survive
4) The resistant bacteria are now more common and reproduce more - this passes on the gene to the offspring
5) You take the drug again and it won’t work as all the bacteria are more resistant

23
Q

How has evolution helped modern biology?

A

Classification - more accurate as it is based more on evolutionary relationships

Antibiotic resistance - know the important of finishing a course to prevent resistant bacteria spreading

Conservation - understand the importance of genetic variation to help populations adapt to the changing environment

24
Q

How are seed banks protecting biodiversity?

A
  • seed bank stores lots of seeds - therefore genetic material.
  • If a plant becomes extinct in the wild the stored seeds can be used to cultivate new seeds and protect biodiversity
25
Q

How do we know if a person is male or female by looking at chromosomes?

A

-We look at the last pair of chromosomes (the gender chromosomes)

Females at birth have XX chromosomes (they look the same)

Males at birth have XY chromosomes (they look different)

26
Q

Ethics of embryo screening?

A
  • There is risk on the child which haven’t been consented to
  • If baby has genetic illness it could promote abortion which some may disagree with
27
Q

Genetic, environmental or both characteristics:

A

GENETIC: Natural eye colour, Natural hair colour, Blood group

ENVIRONMENTAL: scars, tattoos, Hair length

BOTH: Weight, Height

28
Q

Why don’t we have a complete fossil record?

A
  • Most early organisms were soft bodies (don’t fossilise)
  • Fossils may have been destroyed
  • Traces (eg footprint) can be destroyed
  • conditions for fossilisation are rare

Biology (8 decks)

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