2.5 Genetic Variation Flashcards

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1
Q

Gene

A

section of DNA that codes for a protein that influences a characteristic/ trait

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2
Q

Traits

A

The physical expression of genes as characteristics

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3
Q

Sexual reproduction

A

The creation of new living organisms by combining genetic information from two parent organisms

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4
Q

Asexual reproduction

A

Asexual reproduction occurs when an organism makes more of itself without exchanging genetic information with another organism through sex.

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5
Q

Binary fission

A

A single parent cell divides into two daughter cells

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6
Q

Locus

A

Position of a gene on a chromosome

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7
Q

Homologous chromosomes

A

A pair of chromosomes with one maternal and one paternal. They have genes that control the same trait at the same locus

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8
Q

Alleles

A

Different forms of a gene eg. blue or brown eyes

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9
Q

Homozygous dominant

A

An organism that has two dominant alleles for a gene

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10
Q

Heterozygous

A

An organism that has both versions of an allele and the dominant allele will be expressed

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11
Q

Homozygous recessive

A

An organism that has two recessive alleles for a gene

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12
Q

Genome

A

All of the genetic material within an organism

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13
Q

DNA

A

A molecule composed of many nucleotides with a sugar-phosphate backbone. Two DNA polymers coil around each other to form a double helix carrying genetic instructions for the life processes of all known organisms

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14
Q

Nucleotide

A

A single unit of DNA

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15
Q

Name the three parts of a nucleotide

A

A deoxyribose sugar, a phosphate group, and one of four nitrogenous bases (A, T, C, G)

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16
Q

Chromosome

A

A long DNA molecule with part or all of the genetic material of an organism

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17
Q

The genotype of an organism

A

The two alleles an organism posses for a trait eg. Aa

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18
Q

The phenotype of an organism

A

The observable characteristics of an organism due to their genotype

19
Q

Inheritance

A

The passing down of genetic information from one generation to the next

20
Q

Meiosis

A

A type of cell division that produces gametes

21
Q

Gametes

A

Sex cells

22
Q

Eukaryotes

A

Organisms whose cells contain a nucleus

23
Q

Diploid cell

A

Cells that contain an entire set of chromosomes inherited from both parents

24
Q

Haploid cell

A

Cells that only have a single set of chromosomes

25
Q

Fertilisation

A

When one gamete (eg. sperm cell) fuses with another gamete (eg. egg) to form a single zygote

26
Q

Zygote

A

A diploid cell resulting from the fusion of two haploid gametes

27
Q

Punnett squares

A

Simple diagrams that show the possible allele combinations that can occur when two parental gametes are fertilised

28
Q

Mutations

A

A permanent change in an organism’s genetic material

29
Q

Gametic mutations

A

Mutations that can be passed down to offspring, as they occur within the cells of testes/ ovaries and therefore present in gametes

30
Q

Centromere

A

Joins two sister chromatids

31
Q

Sister chromatid

A

A copy of the original chromosome when it has been replicated

32
Q

Why is meiosis important?

A

Meiosis produces gametes that can be fertilised to create a new individual. Meiosis maintains the chromosomal number from generation to generation and promotes genetic diversity/ variation in the population

33
Q

Phenotypic variation

A

The differences in physical features (traits) within a population

34
Q

Genetic variation

A

The number of different alleles within a population

35
Q

Mutagens

A

The factors that cause mutations

36
Q

Where does meiosis occur?

A

Meiosis occurs in specialised germ cells found within sex organs

37
Q

Disjunction

A

The process during meiosis when chromosomes are pulled apart by spindle fibres

38
Q

Spindle fibres

A

Structures that form during cell division to separate sister chromatids

39
Q

Point mutations

A

Mutations that cause one or very few nucleotides in a sequence

40
Q

Chromosomal mutations

A

Mutations involving a long segment of DNA

41
Q

Random fertilisation

A

Egg and sperm cells combine randomly with many different possible combinations

42
Q

Non-heritable/ acquired variation

A

Variation in an individual that can not be passed onto offspring, and usually occur due to environmental factors

43
Q

Why is genetic variation important?

A

Variation ensures that if conditions change (eg. climate, resources, disease, etc.) some individuals will have adaptations that enable them to continue surviving and reproducing. This ensures the survival of a species.