Genetics Flashcards

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1
Q

What are the advantages of sexual reproduction?

A

Provides variation, species can adapt to new environments, a disease is less likely to spread.

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2
Q

What are the disadvantages to sexual reproduction?

A

Time and energy to find mate, it is not possible for an isolated individual.

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3
Q

What is asexual reproduction?

A

Involves only one parent, Organisms produced are exact replicas of their parents.

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4
Q

What are the advantages of asexual reproduction?

A

increase in population, only one parent needed, fast, more time and energy efficient.

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5
Q

What are the disadvantages of asexual reproduction?

A

no variation, species may be suited to only one habitat, disease may effect everyone.

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6
Q

What is meiosis?

A

meiosis produces haploid non-identical sex cells or gametes. These fuse to form a diploid fertilized egg cell.

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7
Q

What does meiosis produce?

A
  1. sperm, egg cells in animals and pollen
  2. pollen and egg cells in plants
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8
Q

What is mitosis?

A

mitosis produces identical diploid cells for growth and repair

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9
Q

What are chromosomes?

A

These are long threads of DNA, which are made up of genes.

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10
Q

What are genes?

A

a gene is a small section of DNA, each gene codes for a particular sequence of amino acids.

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11
Q

What is a genome?

A

the genome is one copy of all an organisms DNA.

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12
Q

Who found out the structure of DNA?

A

James Watson and Francis Crick in 1953.

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13
Q

What does DNA look like?

A

two strands coiled into a double helix.

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14
Q

How is DNA structured?

A

DNA is a polymer made from four different nucleotides. These are arranged in a repeating fashion.

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15
Q

What is the repeating pattern of the four nucleotides in DNA?

A

T-A , C-G , A-T, C-G, T-A, G-C

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16
Q

What nucleotides pair up with eachother?

A

thymine pairs with adenine
guanine pairs with cytosine.

17
Q

Where is the DNA code for protein?

A

The Nucleus

18
Q

How do cells express their genes?

A

by converting the genetic message into protein. This process of protein synthesis occurs in two stages - transcription and translation.

19
Q

What is mutation?

A

A mutation is a change in a gene or chromosome

20
Q

What is natural selection?

A

organisms that are better adapted to an environment are more likely to survive long enough to reproduce and pass on their genes. This leads to evolution

21
Q

What are the causes of mutation?

A
  1. ionising radiation
  2. chemical mutagen, such as tar from cigarette smoke
22
Q

What are the effects of a mutation?

A

change the activity of a protein if they occur within a gene.

23
Q

What are homozygous?

A

two of the same alleles

24
Q

What is a Genotype?

A

the alleles that an organism has.

25
Q

What is a heterozygous?

A

Two different alleles.

26
Q

What is a phenotype?

A

Physical characteristics.

27
Q

What is a recessive gene?

A

only expressed if there are two copies of that allele.

28
Q

What is a dominant gene?

A

a gene that is always expressed.

29
Q

What is an allele?

A

different version of the same gene.

30
Q

What is codominance?

A

Some alleles are both expressed in the same phenotype

31
Q

What are male chromosomes?

A

males have two different sex chromosomes, X Y

32
Q

What are females chromosomes?

A

females have two X chromosomes, XX.

33
Q

What is selective breeding?

A

is when humans breed plants and animals for particular genetic characteristics.

34
Q

What are advantages of selective breeding?

A
  1. new varieties may be economically important, by producing more or better quality food
  2. animals can be selected that cannot cause harm, for example cattle without horns
35
Q

What are disadvantages of selective breeding?

A
  1. reduced genetic variation can lead to attack by specific insects or disease
  2. rare disease genes can be unknowingly selected
  3. creation of physical problems in specific organisms