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Biology GCSE > Topic 3: DNA, enzymes, meiosis, monohybrid genetics, mutations, HGP. > Flashcards

Topic 3: DNA, enzymes, meiosis, monohybrid genetics, mutations, HGP. Flashcards

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1
Q

What shape is DNA

A

A double helix.

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2
Q

What are the four bases?

A 
a,t and c,g (these always go together like that)
adenine
cytosine
guanine
thymine.
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3
Q

What is a nucleotide?

A

A grouping in which a base is attached to a sugar and each sugar is attached to a phosphate group.

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4
Q

What is a mutation?

A

A gene mutation is a change in the order of bases on a strand of DNA which affect anything that that dna section codes for.

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5
Q

What is substitution?

A

It is a mutation in which a base in the DNA sequence is changed, affecting the codon. with a differentDNA codon the mRNA changes as the complementary bases are different. this mean the translation process changes making the tRNA anti codon different to what it should be. With different tRNA, the amino acid is different to what it should therefore changes the shape of the protein.

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6
Q

What are enzymes?

A

Proteins that act as a biological catalyst in order to bring about a specific reaction. e.g. to brake down food.

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7
Q

How do enzymes brake down substrates?

A

The enzyme specific active site collides with the complementary substrate. Activation energy starts the reaction in which the substrate gets broken down into two separate products.

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8
Q

What is activation energy?

A

The energy required for a reaction to take place.

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9
Q

What does denatured mean in enzymatic terms?

A

When the active site changes shape so it is no longer complementary to the substrate due to extreme temperature or Ph.

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10
Q

What is amylase?

A

An enzyme catalyses the reaction from starch into sugars.

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11
Q

What does Lipase do?

A

catalyses the reaction of lipids into fatty acids and glycerol

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12
Q

What do protease do?

A

catalyses he reaction of proteins into amino acids.

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13
Q

What is meiosis?

A

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell and is used to create gametes. for example, a sperm cell has half the number of chromosomes as a normal body cell.

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14
Q

How does meiosis happen?

remember the e otherwise it wont count because mitosis has a similar spelling

A

1) each chromosome is copied
2) move to the edges of the cell
3) The pairs of chromosomes divide into two separate cells
4) These cells divide again into two more cells with half the number of chromosomes. so these cells or gametes only have one copy of each chromosome

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15
Q

What is an allele?

A

A variant of a gene from your parents.

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16
Q

What does heterozygous mean?

A

when the offspring has two different alleles usually one dominant and one recessive. e.g c,C

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17
Q

What does homozygous mean?

A

When the offspring has two of the same alleles. E.g C,C

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18
Q

What is a genotype?

A

A genome is an organism’s complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism.
If a question asks to state the genotype, it is asking for heterozygous or homozygous

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19
Q

What is a phenotype?

A

What the effect of the allele is. e.g eye colour or if you have a genetic disease or not.

20
Q

What is a zygote?

A

A fertilised egg.

21
Q

What does it mean by a recessive allele?

A

An allele that doesn’t show any impact unless paired with another of the same recessive allele (c,c). e.g you need to of the alleles coding for blue eyes to have blue eyes.

22
Q

What does it mean by a dominant allele?

A

An allele that takes control/the one that is seen when the genotype is anything apart from two recessive alleles. It takes dominance over the recessive alleles.

23
Q

How to work out the probability of having a particular genotype.

A

Use a table/ grid(similar to that used in maths for multiplication) with the genotype of one parent at the top and the other at the side. remember dominant (capital) alleles take dominance.

24
Q

What is co-dominance?

A

This is when there are two DIFFERENT dominant alleles and they both take dominance creating a new genotype. most common in blood groups.

25
Q

What is cystic fibrosis?

A

A genetic disease and mutation that cause a build up of mucus in many organs and other small passages.

26
Q

What causes cystic fibrosis?

A

When both copies of the CFTR gene are faulty and don’t work the way they are supposed too. Therefore they don’t make the right protein which makes salt and prevents the cf. If only one of the cftr genes is faulty they will still make sufficient amounts of salt and therefore they are only a CARRIER of cystic f.

27
Q

What is genetic modification?

A

Certain enzymes can cut pieces of DNA with a desired characteristic from one organism, and join them into a gap in the DNA of another organism. This means that the new organism with the inserted genes has the genetic information for one or more new characteristics. For example, humans produce insulin and bacteria are genetically modified to carry that gene and produce insulin.

28
Q

What is the process of genetic modification? / how do they do it.

A

1) choose desired gene from the DNA
2) isolate that gene (cut it out) using a restriction enzyme, to leave a pair of sticky ends
3) The vector (e.g. bacteria for insulin) is cut using the same restriction enzyme also leaving sticky ends
4) .The vector and the isolated gene are joined together by ligase enzyme and inserted back into the vector
5) The genes are transferred to animal, plant or microorganism cells, during early development, which allows them to develop with the desired characteristics.

29
Q

What are the letters of the bases that form the DNA code?

A

A, T

G, C

30
Q

What is transcription?

A

The first part of the processes of making proteins

31
Q

What are the steps of protein synthesis?

A

1) DNA unwinds and mRNA nucleotides attach to their complementary bases, replacing the other strand of DNA
2) mRNA being a single strand can fit through the nuclear pores and goes into the cytoplasm
3) tRNA anti-coden fits together with their complementary mRNA coden with its amino acid attached to the tRNA
4) The tRNA leaves it amino acid and as this process repeats, the amino acids build up into a chain called a protein.

32
Q

What is a substrate?

A

The stuff which gets broken down by an enzyme.

33
Q

What is an allele?

A

Alleles are different forms of a gene. They can be dominant or recessive

34
Q

What is a zygote?

A

a fertilised egg

35
Q

what is cystic fibrosis?

A

a genetic disease caused by both copies of the CFTR gene in chromosome 7 to be faulty. This is because of a mutation causing the wrong protein to made not the correct salt transportation protein. If you suffer from cystic fibrosis you will have build up of mucus in many organs like the lungs.

36
Q

What are sticky ends?

A

A short section of unpaired bases in the DNA usually cut by a restriction enzyme.

37
Q

How do you calculate the rate of reaction

A

amount of reactant used OR product formed/time

38
Q

How do you calculate rate of enzyme activity?

A

1/time

39
Q

What is polymerase?

A

a substance which aids the RNA nucleotides binding to the complementary DNA

40
Q

what are the advantages of asexual and sexual reproduction?

A

Asexual reproduction: quick and doesn’t require a mate/fertilisation
Sexual reproduction: allows for variation between offspring, reducing the chances of genetic disease and increased chances of survival

41
Q

What is the question asking for if it says ‘state the genotype’?

A

homozygous or herozygous

42
Q

What is a plasmid?

A

A loop of extra DNA in a bacterial cell.

43
Q

Explain the iodine test

A

A few drops of iodine solution put into a solution to test for starch
Colour of negative result: Yellow/orange
Colour of positive result: blue/black

44
Q

Explain the benedict’s solution test

A

Add benedict’s solution to the solution and heat at 95’c to test for reducing sugars

Colour of negative result: Blue
Colour of positive result: Green -> orange -> red
(depending on how much sugar present)

45
Q

Explain the biuret test

A

Contains potassium hydroxide solution and copper sulfate solution. Add this to the solution to test for protein.

Colour of positive result: pale blue
Colour of negative result: pale purple

46
Q

Explain the ethanol test

A

Add ethanol to a food solution to test for fat.

Colour of negative result: clear
Colour of positive result: cloudy

Biology GCSE (12 decks)

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