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Biology Paper 1 > CB3 - Genetics > Flashcards

CB3 - Genetics Flashcards

1
Q

What are the advantages and disadvantages of Asexual reproduction?

A

Advantages:
- Can produce offspring very quickly because of reproductive cycle
- Only one parent is needed and can reproduce without a mate
Disadvantages:
- No genetic variation between population so if any environment changes, conditions might affect whole population

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2
Q

What are the advantages and disadvantages of Sexual reproduction?

A

Advantages:
- Creates genetic variation which have different characteristics
- This can lead to natural selection and evolution
Disadvantages:
- Takes more time and a lot of energy
- You need two mates/parents and this can be a problem if they are isolated.

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3
Q

Describe cells produced by meiosis?

A

Produces 4 genetically different daughter cells (Gametes) and they are haploid cells

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4
Q

Why are haploid cells produced via meiosis?

A

When 2 gametes fuse, cell will have full genetic material.

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5
Q

Describe DNA as a polymer?

A

Made up of lots of repeating units called nucleotides. Each contain 1 sugar molecule, 1 phosphate molecule and 1 one base. There are 4 bases: A, T, C, and G. A pairs with T and C pairs with G. DNA has two strands coiled together in a shape of double helix. Complimentary bases are joined with weak hydrogen bonds.

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6
Q

What is a Genome?

A

Entire DNA of an organism.

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7
Q

What is a Gene?

A

A section of DNA which codes for a protein.

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8
Q

How can DNA be extracted from fruit?

A
  1. Mash some strawberries, put them in beaker containing detergent and salt and mix
  2. Filter mixture to get insoluble cell out
  3. Add some ice-cold alcohol to filter mixture
  4. DNA will come out solution as it is not soluble in cold alcohol. It will appear as white stringy precipitate.
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9
Q

Explain how order of bases in DNA decide order of amino acid in protein?

A

Section of DNA codes for particular protein. Each amino acid is coded by a sequence of 3 bases (Base triplet). Amino acid are joined together to make protein.

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10
Q

Explain what is Transcription?

A

RNA polymerase binds to a non-coding DNA in front of gene.
Two DNA strands unzip and RNA move along one strand.
Uses coding DNA in gene as template for mRNA. Base pairing between DNA and RNA to make sure mRNA is complimentary.
mRNA moves out the nucleus and joins with ribosomes.

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11
Q

Explain what is Translation?

A

Amino acids are brought by tRNA.
Order in which amino acid are brought matches of base triplets in mRNA (Codons).
tRNA structure is called an anticodon - Complimentary to codon for amino acid.
Amino acid are joined together and fold up into a polypeptide chain.

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12
Q

Describe how non-coding DNA affects binding of RNA polymerase?

A

If mutation in DNA it could affect ability of RNA to bind to it, might make it easier or harder. How well RNA binds affect how much mRNA is transcribed and how much protein is made. Depending of function of protein, phenotype may be affected.

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13
Q

Describe how coding DNA can affect sequence of amino acid?

A

If mutation in a gene, might code for a diff sequence of amino acid which can change shape of protein. Might change the Phenotype.

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14
Q

Describe the work of Mendel in discovering basis of genetics?

A

Crossed tall pea plants and dwarf pea plants - Offspring produced were al tall plants. Bred 2 tall plants and produce 3:1 tall to dwarf plants.

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15
Q

What had Mendel showed?

A

Characteristics were determined by separately inherited passed on from each parent. The ratio shows Tall was dominant.

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16
Q

What were the difficulties of understanding inheritance before mechanism was discovered?

A

Mendel’s work was cutting edge and new to scientist. “Hereditary units” are now gene but at the time, scientist had no idea about DNA.

17
Q

Explain why there are differences in inherited characteristics?

A

Diff forms of same gene is called alleles. Each copy of gene may be diff allele. Diff combination of allele gives us diff characteristics.

18
Q

What is a Chromosomes?

A

Long, coiled up of DNA.

19
Q

What is a Gene?

A

A section of DNA.

20
Q

What is an Allele?

A

Different forms of same gene.

21
Q

What is Homozygous?

A

Two alleles for particular gene that are the same.

22
Q

What is Heterozygous?

A

Two alleles for particular gene are diff.

23
Q

What is genotype?

A

Combination of alleles.

24
Q

What is Phenotype?

A

The physical characteristics.

25
Q

Explain monohybrid squares inheritance?

A

Inheritance of a single characteristics. A monohybrid cross can be used to show how recessive and dominant traits for single characteristics are inherited.

26
Q

Punnet Square

27
Q

How can the gender of the offspring is determine at fertilisation?

A

There are 23 matched pairs. 23rd par could be XX (Female) or XY (Male). There is a 50% chance to have a boy or girl.

Genetic diagram

28
Q

How are sex-linked genetic disorders are inherited?

A

Women need two copies of recessive allele. while man only need one. A woman with one is a carrier and can pass the allele on. 25% chance of being colour blind.

29
Q

Describe inheritance of ABO blood group?

A

Blood group I^A and I^B are codominant. I^AI^B would be blood group AB. I^O is recessive. I^AI^O would be blood group A. I^OI^O would be blood group O.

30
Q

Describe the causes of genetic variation?

A

Species is caused by having diff alleles which can lead to diff in phenotype. Can be caused by new alleles through mutation. Sexual reproduction causes genetic variation since alleles combines in diff ways.

31
Q

Describe the cause of environmental variation?

A

Phenotypes are also known as acquired characteristics - organisms acquires during lifetime.

32
Q

What were the outcome of Human Genome project?

A

Helped to identify 1800 genes related to disease which was huge potential benefits for medicine.

33
Q

What were the potential application within medicine?

A

There were 3 :
- Prediction and prevention of disease
- Testing and treatment for inherited disorders
- New and better medicine

Biology Paper 1 (5 decks)

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