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Biology > Topic 3 - Genetics > Flashcards

Topic 3 - Genetics Flashcards

1
Q

What is sexual reproduction

A

Genetic information from two organisms ( a father and mother ) is combined to produce offspring genetically different to either parent
In sexual reproduction the parent produce gametes. In Animals this is sperm and egg cells

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2
Q

Gametes

A

The reproductive cells of a plant or animal. These are HAPLOID ( only 1 set of chromosomes )

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3
Q

Zygote

A

At fertilisation, the male gamete fuses with the female gamete to produce a ferilised egg called a ZYGOTE. This has the full set of chromosomes - DIPLOID

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4
Q

How does a zygote develop into an embryo?

A

It undergoes cell division by mitosis.
This embryo inherits characteristics from both parents, as it has recieved a mixture of chromosomes

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5
Q

How are gametes produced?

A

By meiosis

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6
Q

Meiosis vs mitosis

A

Mitosis produces clones. - Diploid
Meiosis doesnt produce identical cells - Haploid

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7
Q

Where does meiosis happen in the body?

A

In the reproductive organs

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8
Q

How does the FIRST DIVISION of meiosis

A
  1. before the cell divides, it duplicates its DNA
  2. The chromosoes line up in pairs at the centre of the cell - one of the pair from the organisms mum, one from their dad
  3. The pairs are then pulled apart, so each one only has 1 copy of each chromosome - some of the mum nad some of the dads chromosomes go into each cell

Each new cell with have a mixture of the mothers and the fathers chromos

Creates Genetic variation

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9
Q

How does the SECOND DIVISION of meiosis

A
  1. The chromosomes line up in the centre again, but ovbi not in pairs dun
  2. The chromatids of the chromosomes are pulled apart
  3. This creates 4 Haploid daughter cells - these are the Gametes

The gametes are all genetically different

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10
Q

What are the ADVANTAGES of ASEXUAL reproduction

A
  • can produce lots of offspring very quickly - This allows organisms to colonise a new area very quickly
    -One parent is needed - Organisms can produce whenever conditions are favourable, without having to wait for a mate
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11
Q

What are the DISADVANTAGES of ASEXUAL reproduction

A
  • there is no genetic variation in the population
  • ## Suceptable to environment changes, they cannot adapt
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12
Q

What are the ADVANTAGES of SEXUAL reproduction

A
  • Creates Genetic variation
  • Not suceptable to environment changes - adaptability
  • Natural selection and evolution makes these always better suited to their environment conditions
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13
Q

What are the DISADVANTAGES of SEXUAL reproduction

A
  • Takes more time and energy than Asexual reproduction, organisms produce less offspring in their life
  • Two parents are needed, a problem is an organism is isolated.
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14
Q

What is a DNA strand made of?

A

Dna is a polymer made up of Nucleotides

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15
Q

What does each nucleotide in a DNA consist of?

A

A sugar, a phosphate group and one base

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16
Q

What do the Sugar and phosphate group form in DNA?

A

The strands, the sugar and phosphate group alternate

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17
Q

Where are the bases in DNA and what 4 bases are there?

A

The bases join to the sugars
Adenine - Thymine
Cytosine - Guanine

18
Q

What is complementary base pairing?

A

The sugar bases will correspond and match up to another sugar base. They are held together by weak hydrogen bonds
A - T
C - G

19
Q

How is DNA stored?

A

as chromosones

20
Q

What are chromosomes

A

Long, coiled up peices of DNA found in Eukaryotic cells

21
Q

What is a gene?

A

A section of DNA on a chromosome that codes for a particular protien with a specific sequence of bases

22
Q

What is a genome?

A

all of an organisms DNA

23
Q

How do you extract DNA from fruit cells?

A

Mash strawberries and put in a beaker containing a solution of detergent and salt
Detergent - Break down cell membranes to release DNA
Salt - Make the DNA stick together
Filter the mixture - get froth and big insolule bits out.
Gently add some ice cold alcohol to the filtered mixture
The DNA will start to come out of the solution as it is not soluble in ice cold alcohol. It will appear as a stringy white precipitate that can be fished out with a glass rod

24
Q

What is the use of DNA?

A

DNA controlls the product of protiens in a cell ( protien synthesis)
DNA molecules contains a genetic code on which protien is built. The protien determines how the cells in the body work

25
Q

What is protien synthesis?

A

The production of protien

26
Q

What are protiens made up of?

A

Amino acid chains folded in a specific way with each protien having its own specific number and order of amino acids. These amino acids are joined together by the order of the bases in the gene

27
Q

Why do different protiens have different functions?

A

The amino acids fold up to give each protien a different, specific shape

28
Q

How are amino acids coded for?

A

A base triplet

29
Q

What is a base triplet?

A

A sequence of 3 bases in a gene

30
Q

What is a triplet code?

A

A code based on base triplets

31
Q

What does a change in bases of a gene cause?

A

A genetic mutation. Some of these mutations can change an organisms phenotype

32
Q

How can a mutation occur?

A

Cell division or environmental factors

33
Q

How are mutations in non-coding DNA caused?

A

RNA polymerase attaches to DNA bases in the front of a gene. A mutation in this non- coding region may result in the RNA not binding well, reducing transcription.

34
Q

What are alleles?

A

different forms of the same gene

35
Q

Heterozygous

A

Both genes are different

35
Q

Homozygous

A

Alleles are the same

36
Q

Genetic variation

A

Caused by the different alleles inherited during sexual reproduction

37
Q

Environmental variation

A

affected by the surroundings

38
Q

Discontinuous variation

A

Where the data can only take a limited set of values

39
Q

Continuous Variation

A

the data can be any value in a range

40
Q
A

Biology (3 decks)

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