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chemistry > Inheritance > Flashcards

Inheritance Flashcards

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1
Q

define a gene

A

A gene is a sequence of nucleotides/ DNA that codes for a specific polypeptide

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2
Q

define a allele

A

A particular version of a gene
eg. Blood type in humans

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3
Q

what are the 2 types of alleles?

A

Dominant and recessive alleles

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4
Q

what are dominant alleles?

A
  • Dominant alleles are always expressed when present
  • written using upper-case
    Aa> dominant allele is A
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5
Q

what is a recessive allele?

A
  • only expressed is the dominant allele is not present
  • written using lower-case letters
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6
Q

how many chromosomes does a human cell have?

A

46 chromosomes, that are divided into 23 pairs of homologous chromosomes

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7
Q

what are homologous chromosomes?

A
  • they have the same gene on the same loci
  • they may or may not have the different alleles
    > shape : two ears on both sides and one little circle in the middle
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8
Q

what is a genotype?

A

AA, aa, Aa,

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9
Q

what are the genotype for homozygous dominant chromosomes?

A

AA

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10
Q

what are the genotype for Heterozygous chromosomes?

A

Aa, aA

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11
Q

what is the genotype for homologous recessive chromosomes?

A

aa

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12
Q

define phenotype?

A

appearance,
colour?, skin colour, curly hair?, spots

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13
Q

can the environment change ur phenotype?

A

Yes! our phenotype can change with effects to the environment
eg. when provided with better education system, a person can become more intelligent,

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14
Q

methods to find the offspring outcomes for a cross between 2 parents

A

using a punnet square, or the use of genetic diagrams

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15
Q

Draw a punnet square and predict the outcomes!
BB x Bb

A

1:1
All offspring will show dominant trait

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16
Q

Draw a punnet square and predict the outcomes!
Bb x Bb

A

1:2:1
BB:Bb:bb
3:1
dominant trait: recessive trait

17
Q

What are the 2 types of variation?

A

Discontinuous and Continuous variation

18
Q

What is Discontinuous variation?

A
  • has distinct categories/groups
  • affected by one or a few genes only
    -not affected by the environment
    eg. Sickle cell haemoglobin, dimples, ABO blood group, double eyelid

https://scienceaid.net/images/6/63/variation.png

19
Q

What is continous variation?

A
  • has no distinct categories
  • affected by many genes
  • affected by the environment
    eg. Height, weight, skin tone, intelligence

https://scienceaid.net/images/6/63/variation.png

20
Q

what are the 2 types of selection

A

natural and artificial selection

21
Q

what is natural selection?

A

selective reproduction success due to natural factors

22
Q

what is artificial selection?

A

Selective reproductive success due to human interference/choice

23
Q

what is meant by variation in a population?

A

refers to variation in the characteristics and traits between individuals in a population.

24
Q

State a way genetic variation can arise in a population?

A

Mutation

25
Q

which sex chromosomes does a male have?

A

XY chromosomes

26
Q

which sex chromosomes does a female have?

A

XX chromosomes

27
Q

Define mutation

A

Mutation is the spontaneous/ random change to the structure of a gene or chromosome number.

28
Q

What causes mutation?

A
  • Radiation (UV light/gamma rays)
  • mutagens
29
Q

can mutations be inherited?

A

Mutations in stomatic cells are not inherited, but mutagens in gametes can be inherited
Stomatic cells: all cells accept sex cells

30
Q

What are gametes

A

Human sex cells

31
Q

What are the 2 types of mutation

A

Gene mutation and Chromosome number mutation

32
Q

What is Gene mutation?

A

it is the change in nucleotide sequencing resulting in a different polypeptide being produced
eg. Sickle cell anaemia

33
Q

What is sickle cell anaemia? (for content)

A

Red blood cells normally produce normal haemoglobin that can bind to oxygen and carry oxygen to other parts of the body.

If the haemoglobin gene is mutated, the normal haemoglobin protein cannot be formed

In sickle cell anaemia, there is a mutation in the Hb gene due to a change in the nitrogenous base sequence. The result is sickle cell haemoglobin (HbS) which cannot bind to oxygen normally. Instead under low O2 conditions, it will polymerize and bind to the cell surface membrane, and cause the RBC to change shape, into sickle cell, becoming very fragile and inelastic.

Sickle cells die/burst very easily. If a person has many sickle cells the death of these cells means they lose O2 carrying capacity.

Thus those suffering from sickle cell disease generally have more difficulty breathing than others, and die more easily

34
Q

Explain gene mutation using a named example?(olevel qn)- 4m

A

Gene mutation is a spontaneous/random change in the nitrogenous base sequence. An example of gene mutation is sickle cell anaemia.
The haemoglobin gene is mutated and produces abnormal haemoglobin that causes the red blood cells to become sickle shaped and burst more easily. Th oxygen carrying capacity of blood is decreased.

35
Q

What is chromosome number mutation?

A

it is the change in chromosome number due to non-disjunction of homologous chromosomes during meiosis (cell division) sister chromatids failing to separate during cell division.
eg. Down syndrome( Trisomy 21)

36
Q

What is down syndrome?

A

In human cells, there are normally 46 chromosomes (23 from the father and 23 from the mother)

When gametes are formed during meiosis, the homologous chromosomes pair up, then split up into different cells so that each gamete daughter cell receives only 23 chromosomes.

If there is non-disjunction of chromosome 21(gamete) during meiosis, one gamete will have 24 chromosomes instead of 23, it will have an extra copy of chromosome 21.

37
Q

how does down syndrome occur?

A
  • Egg cell with 23 chromosomes+ sperm cell with 24 chromosomes
  • Egg cell with 24 chromosomes+ sperm cell with 23 chromosomes
38
Q

what are the chemicals that have alot of radiation causing mutations?

A

UV light and Gamma rays

chemistry (10 decks)

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