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AS level Biology > Section 4 - DNA, genes and protein synthesis > Flashcards

Section 4 - DNA, genes and protein synthesis Flashcards

1
Q

What can reduce species diversity in agriculture?

A

Monocultures

Overgrazing

Draining wetlands

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2
Q

How can we compare genetic diversity between species?

A

DNA sequences Observable characteristics Amino acid sequences

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3
Q

During transcription, what is reading the open DNA to make a sequence of complementary bases?

A

RNA polymerase

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4
Q

How do you write the scientific names of species?

A

Underlined Italics First letter of first name uppercase

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5
Q

Write the taxonomic ranks in order

A

Domain Kingdom Phylum Class Order Family Genus Species

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6
Q

What is artifical classification?

A

single or at most only a few characteristics to group plants

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7
Q

Which bases pair with 3 hydrogen bonds?

A

G to C

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8
Q

Where else can DNA be found in eukaryotic cells?

A

Mitochondria Chloroplasts

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9
Q

What type of bond is formed between the amino acids during translation?

A

Peptide

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10
Q

Why is splicing needed during transcription?

A

To remove introns

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11
Q

Which bases pair with 2 hydrogen bonds?

A

A to T

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12
Q

What is a triplet on a mRNA molecule referred as?

A

codon

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13
Q

What are some facts about mRNA?

A

Short lifetime Single stranded Present in transcription Present in translation

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14
Q

What is different from pre-mRNA and mRNA?

A

Introns are removed

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15
Q

What type of classification groups organisms based on evolutionary relationships?

A

Phylogenetic classification

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16
Q

Define the term allele.

A

The different characteristics coded for by the same gene

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17
Q

How do we name species?

A

Binomial system

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18
Q

What is a triplet on a tRNA molecule referred as?

A

Anticodon

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19
Q

Define the term gene.

A

A section of DNA at a specific position

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20
Q

What classifies organisms into the domain bacteria?

A

70S ribosomes Cell walls contain murein No histones associated with DNA

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21
Q

How could you describe other types of eukaryotic DNA? (not found in the nucleus) *

A

Short Not associated with proteins

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22
Q

What are the 3 domains?

A

Eukarya Bacteria Archaea

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23
Q

What is the role of rRNA?

A

Makes up ribosomes

24
Q

What is the protein associated with DNA?

A

Histone

25
Q

What do polypeptides make up?

A

Proteins

26
Q

What do enzymes do?

A

Control chemical reactions they are responsible for an organisms development and activities.

27
Q

What is a locus?

A

A gene located at the particular position on the DNA molecule.

28
Q

What does DNA code for?

A
  • Amino acid sequence of polypeptide - Functional RNA, including ribosomal RNA and transfer RNAs
29
Q

How many bases code for each amino acid?

A

3

30
Q

How many naturally occurring amino acids are there?

A

20

31
Q

What are the four different bases in DNA?

A

Adenine, guanine, cytosine and thymine.

32
Q

How many different codes are produced with three bases?

A

64 this satisfies the requirement for 20 amino acids

33
Q

Explain the features of genetic code

A

Few amino acids are coded for by only a single triplet. The remaining AA are coded for by 2-6 triplets each known as degenerate code Start - codes for polypeptide and always the same triplet. Stop codes mark the end. Codes are non-overlapping. Code is universal

34
Q

What is degenerate code?

A

Most amino acids are coded for by more than one triplet

35
Q

What are the coded for the start of a DNA sequence?

A

Codes for a polypeptide with amino acid methinonine

36
Q

Why does DNA provide indirect evidence for evolution?

A

The code is universal with few minor exceptions as each triplet codes for the same amino acid in all organisms.

37
Q

What are exons?

A

Genes that code for amino acids.

38
Q

What are introns?

A

Non-coding genes for DNA.

39
Q

What are the two types of cells?

A

Prokaryotic and eukaryotic cells.

40
Q

What are the genetic differences between Pro and Eukaryotic cells?

A

Pro - DNA is shorter, in a circle and not associated with protein molecules. No chromosomes. Eu- Longer molecules, line in association with proteins called histones forming chromosomes

41
Q

What do histones do?

A

In eukaryotic cells that form chromosomes.

The DNA in chromosomes are held together by histones.

42
Q

What is the DNA like inside the prokaryotic cells?

A

Short, circular and not associated with proteins.

43
Q

What is a chromatid?

A

One of two threads of a chromosome.

44
Q

In an average human cell, what is the length of DNA?

A

Around 2m

45
Q

where do humans get their two types of chromosomes?

A

One complete set from the egg - maternal chromosomes.

One complete set from the sperm - paternal chromosomes.

These are homologous pairs and the total number is referred to as the diploid number.

46
Q

What is the diploid number in humans/

A

46 chromosomes.

23 sets

47
Q

What is a homologous pair?

A

Always two chromosomes that carry the same genes but not necessarily the same alleles of the genes.

48
Q

What is an allele?

A

One of a number of alternative forms of a gene.

49
Q

What is a gene?

A

Genes are sections of DNA that contain coded information in the form of specific sequences of bases.

Each gene exists in two, occasionally more, different forms.

Each of these forms is called an allele.

50
Q

What is a mutation?

A

Any changes in the base sequence of a gene produces a new allele of the gene and results in a different sequence of amino acids being coded for.

51
Q

What can a mutation lead to?

A

The production of a different polypeptide, and hence a different protein.

Sometimes this different protein may not function properly or may not function at all.

When the protein produced is an enzyme it may have a different shape.

The new shape may not fit the enzymes substrate.

As a result, the enzyme may not function and this can have serious consequences for the organism.

52
Q
A
53
Q

how many different types of tRNA are there?

A

60 different.

A particular tRNA has a specific anticodon and attaches to a specific amino acid.

Each amino acid, therefore, has one or more tRNA molecules, with its own anticodon of bases.

54
Q

What does mRNA do ones it has passed out of the nuclear pores?

A

determines the synthesis of a polypeptide.

55
Q

How are polypeptides made?

A
  • Ribosome becomes attaches to start codon at one end of the mRNA molecule
  • tRNA molecule with complementary anticodon sequence moves to the ribosome and pairs with a codon on the mRNA. tRNA carries specific amino acid.
  • tRNA molecule with complementary anticodon pairs with the next codon on the mRNA.
  • The two amino acids in tRNA are joined by a peptide bond using an enzyme and ATP which is hydrolysed to provide the required energy.
  • The ribosome moves to the third codon linking the amino acids.
  • As this happens the first tRNA is released from its amino acid and is free to collect another amino acid from the pool in the cells
  • The process continues up to 15 amino acids per second until the chain is built up.
  • Continue until reaching the stop codon.
57
Q

In what stage of protein synthesis is linked with a number of polypeptide chains joining?

A

quarternary structure

58
Q

What normally happens to the polypeptide after translation?

A
  • polypeptide is coiled or folded producing its secondary structure
  • the secondary structure is folded producing tertiary structure
  • different polypeptide chains along with an non-protein groups are linked to form the quaternary structure.

AS level Biology (11 decks)

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