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Biology > Chapter 3 - Genetics And DNA > Flashcards

Chapter 3 - Genetics And DNA Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

DNA stands for what?

A

Deoxyribose Nucleic Acid

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2
Q

What does DNA control ?

A

The production of proteins

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3
Q

What are the bases C, G, T and A called and what do their order make?

A

Cytosine, Guanine, Thymine and Adenine and the order of them makes your genome, your genetic code

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4
Q

What does Adenine pair with? It’s complimentary base?

A

Thymine

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5
Q

What does Cytosine always pair with? It’s complimentary base?

A

Guanine

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6
Q

What is a nucleotide ?

A

What forms nucleic acids such as DNA. A compound made up of , in DNA , the deoxyribose, sugar, the phosphate and one of the bases

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7
Q

What is DNA?

A

A polymer (polynucleotide - made of molecules) , a large molecule made up of subunits called nucleotides (monomers)

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8
Q

What is said to be the backbone of DNA?

A

DNA has a sugar and phosphate backbone with a base

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9
Q

How many strands of nucleotides does DNA consist of?

A

2

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10
Q

What shape is DNA?

A

A double helix

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11
Q

In a strand of DNA , sugar and phosphate is on the outside whilst what are on the inside?

A

The bases

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12
Q

What are the strand of nucleotides held together by?

A

Hydrogen bonds

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13
Q

How many different types of amino acids are there and how many do humans have?

A

22, 20

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14
Q

What are the 4 nucleotides in mRNA?

A

Adenine, uracil, guanine, cytosine

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15
Q

What are codons / triplets and what do they do?

A

A codon is a group of 3 bases in the genetic code which controls the production of particular amino acids in the cytoplasm of the cell

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16
Q

How many combinations of codons are possible in humans?

A

64

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17
Q

What is meant by humans having a degenerate code and why is it important?

A

Degenerate code means we have more combinations than we need so it is a defence against mutations as some “spelling mistakes”can be made without changing what the code does, however this is not always the case

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18
Q

Which is smaller RNA or DNA? Why is this the case?

A

RNA because it can exit the nuclear envelope, which has pores, to give amino acids to other ribosomes to form protein, but the DNA cannot so it stays safe inside the nucleus

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19
Q

Out of the 3 bases in a codon which one can most likely change without changing the production of the amino acid? Does this have a name?

A

The 3rd base can usually change, this is called the wobble base

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20
Q

What does the protein helicase do?

A

It unpacks an organisms genes

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21
Q

What is a transcription?

A

The process by which the genetic code in one strand of DNA is used to make mRNA

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22
Q

What is a template strand?

A

The strand of DNA molecule that RNA polymerase uses to make mRNA

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23
Q

What is mRNA and what does it stand for?

A

A single strand of RNA produced in transcription, messenger Ribonucleic Acid. Messenger RNA carries the instruction for protein

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24
Q

What is tRNA and what does it do?

A

Transfer Ribonucleic Acid helps decode a mRNA sequence into a protein

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25
Q

What is an allele ?

A

Different versions of genes, for example for the eye colour gene may have one version / allele that can cause dark eyes and another allele that can cause pale eyes

26
Q

What is a genotype?

A

What version of alleles your genes have

27
Q

What is a phenotype?

A

What does it look like, you only know this once the organism has been born

28
Q

How many copies of genes do we inherit?

A

2, one from each parent

29
Q

What 2 different types of alleles can you inherit that changes your phenotype?

A

Dominant and recessive

30
Q

How many recessive alleles do you need to inherit to change you phenotype? What about dominant?

A

You need 2 recessive alleles to inherit that gene, one from each parent, whereas you only need 1 dominant gene to inherit that characteristic / allele.

31
Q

Dominant alleles produce functioning proteins but what do recessive alleles produce?

A

Non functioning proteins

32
Q

What do you call an organism when it has 2 of the same alleles ? (BB, bb)

A

Homozygous dominant

33
Q

What do you call an organism that has 2 different alleles ? (Bb)

A

Heterozygous

34
Q

How do you know if your heterozygous or homozygous dominant?

A

You will only know if your heterozygous if you take a DNA test, that is the same for homozygous dominant unless you have recessive characteristics like blonde hair or blue eyes

35
Q

How can you show the probability of a certain gene being passed on?

A

By using a punnet square

36
Q

Name all the blood groups and state how many alleles they are controlled by

A

AB, A, B and O

They are controlled by 3 different alleles

37
Q

In blood groups what do the + and - tell you?

A

Slight differences in characteristics, + in common and - may effect pregnancy

38
Q

What is an antigen and where is it located on a blood cell?

A

It is located on the surface of the red blood cell and tells the body what cell it is, whether its its own or not

39
Q

Whats special about Os antigen?

A

It has no antigen so people with O blood are “universal donors” as there blood can be transfused into any other person without leading their body to fighting it

40
Q

Which ones dominant and which ones recessive, O and AB?

A

O recessive and AB is dominant

41
Q

What are antibodies?

A

What does the killing of unknown cells

42
Q

What are the antibodies of blood group O, A and B

A

B is A
A is B
And O is A+B

43
Q

What is special about A+Bs antibodies?

A

It doesn’t have one so people with A+B blood can have any other blood so they are “universal receivers”

44
Q

What is a mutation?

A

The changing of the structure of genes, this can be the sequence of single bases in DNA or the whole chromosome

45
Q

What are the 4 main types of mutation that can occur in DNA and what does each one do?

A

Substitution, one letter is swapped for another
Addition, where letters are added
Deletion, where letters are subtracted
Inversion, where he whole code is flipped the other way round

46
Q

Which 2 of the 4 main types of mutations are the worst and why? (Clue: how the gene is read)

A

Addition and deletion are often the worse as changes the whole of the genetic code in that strand of DNA because it is read in codons so all the codons are changed

47
Q

What are some examples of what causes mutations?

A

Ultraviolet light, chemicals in cigarette smoke, chemicals in environment, background radiation in environment, they can just happen spontaneously

48
Q

How are mutations bad?

A

They can cause cancers

49
Q

How can mutations be good?

A

They cause variation in species, can protect people against diseases for example if ancestors were immune to plague and you have 2 copies of this you are immune to the plague and HIV

50
Q

Give an example of a chromosomal mutation

A

Down syndrome occurs when an addition takes place on the whole of a chromosome

51
Q

What are the 2 types of variation and what are they both?

A

Genetic variation, different characteristics as a result of mutations and sexual reproduction
Environmental variation, characteristics caused by an organisms environment

52
Q

What does continuous variation and discontinuous variation mean and what variation group do they usually belong to?

A

Continuous variation tends to be environmental and discontinuous variation tends to be genetic as you are or are not something

53
Q

What is a chromosome made up of?

A

One long coiled up strand of DNA

54
Q

What enzyme is used to synthesise DNA from RNA?

A

Reverse transcriptase

55
Q

How are gametes, used as one half of an offsprings DNA, formed? By which process?

A

Meiosis

56
Q

What are the main stages in meiosis?

A

Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, then all of these again.

57
Q

Describe all the stages in meiosis

A

Prophase to Telophase is the same as in mitosis
However, after cytokinesis it then carries on, without interphase, straight into prophase again with both of the daughter cells. This means that they are split in half (so each gamete has half a set of DNA) with different sets of chromosomes, as in both prophases the chromosomes swap some DNA in cross over. This creates 4 non identical daughter cells

58
Q

How is it made sure 4 daughter gamete cells are genetically different?

A

During both prophases cross over occurs as chromosomes are moved around by centrosomes and get tangled up and swap some DNA, in the second prophase the DNA gets swapped whilst the chromosomes are free in the cytoplasm in prophase, this is done in each of the 2 daughter cells making them different, then this DNA is pulled in half making all 4 daughter cells genetically different, and very unlikely to ever be created the same again. This is what gives us a large range of gene variation.

59
Q

What are the 2 stages of making proteins out of the genetic code if DNA?

A

Transcription, getting the code out of the nucleus to the ribosomes with mRNA
Translation, when the mRNA is bound to a ribosome and the protein is assembled

60
Q

What does transfer RNA (tRNA) do?

A

Make sure amino acids are brought to the the ribosome in the correct order, as the anticodons they present are checked against the codon of the mRNA to make sure the amino acid is correct

61
Q

What is the last stage of translation?

A

The amino acids, on pace checked by the tRNA, are joined together in the ribosomes. This makes a protein the DNA coded for

Biology (7 decks)

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