Storing and Using Genetic Information

Question 1

What is a phenotype?

Answer 1

Physical manifestation of genotype

Question 2

What is a genotype?

Answer 2

All of the genes in our DNA, even the ones that are not expressed

Question 3

Why are proteins functionally different?

Answer 3

Due to their different structures

Question 4

What does the structure of a protein depend on?

Answer 4

The primary structure (sequence of amino acids)

Question 5

What is DNA?

Answer 5

A chain of nucleotide monomers that contains all of our genetic information

Question 6

What does each nucleotide contain?

Answer 6

Sugar

Base

Phosphate group

Question 7

What structure does DNA form?

Answer 7

Double helix

Question 8

How many bases is there per turn of the helix?

Answer 8

10

Question 9

How do polypeptide chains of DNA run to each other?

Answer 9

Antiparralel to one another

Question 10

How are the groves in DNA described?

Answer 10

Major and minor groves which is important for the interaction of proteins

Question 11

What is the pairing of bases called?

Answer 11

Compliment base pairing

Question 12

What bases pair with what in DNA?

Answer 12

Thymine paires with adenine

Guanine pairs with cytosine

Question 13

What does compliment base pairing happen?

Answer 13

Due to the structures of the bases:

Thymine pairs with ademine due to both forming 2 hydrogen bonds

Guanine pairs with cytosine due to both forming 3 hydrogen bonds

Question 14

What bases form 3 hydrogen bonds with each other?

Answer 14

Cytosine and guanine

Question 15

What bases form 2 hydrogen bonds with each other?

Answer 15

Thymine and adenine

Question 16

What is the site of a cells genetic information (DNA)?

Answer 16

Nucleus

Question 17

Where does the first step of protein production take place and what is this?

Answer 17

DNA replicaiton which takes place in the nucleus

Question 18

What does each nucleus contain?

Answer 18

A nucleolus which can take up to 25% of its volume and is where transciption and assemble of rRNA takes place

Question 19

Where does transcription and assemble of rRNA take place?

Answer 19

Nucleolus

Question 20

What is DNA packaged into?

Answer 20

Thread like structures called chromosomes

Question 21

When are chromosomes visible?

Answer 21

During cell division

Question 22

What is a chromosome?

Answer 22

Single piece of DNA containing many genes, regulatory elements and other nucleotide sequences

Question 23

How many chromosomes does a human have?

Answer 23

46

Question 24

What can the structure of chromosomes be described as?

Answer 24

Highly ordered to contain vast amounts of DNA

Question 25

What is the process of packaging chromosomes?

Answer 25

1) Chromatin is the double stranded helical structure of DNA 2) DNA is packed with histones to form nucleosomes, with each consiting of 8 histones 3) Binded with H1 histone to form chromatosome 4) Folded up and tightly coiled to produce fibre called chromatid of the chromosome

Question 26

What is chromatin?

Answer 26

Mixture of DNA, proteins and RNA thay packages DNA within the nucleus

Question 27

What are the 2 forms of chromatin?

Answer 27

Heterochromatin (condensed) Euchromatin (extended)

Question 28

What must the chromatin do for transcription and replication to occur?

Answer 28

Open up to allow enzymes to access the DNA template

Question 29

What are the 2 mechanisms for opening up chromatin to allow replication or transcription to occur?

Answer 29

Histones can be enzymatically modified Histones can be displaced by chromatin remodelling complexes

Question 30

What should be noted about both processes of opening up chromatin?

Answer 30

They are reversible

Question 31

What does it mean that DNA replication is semi conservative?

Answer 31

Half of each new molecule is old DNA and half is new DNA

Question 32

What does it mean that DNA replication is bi-directional?

Answer 32

DNA polymerase is onlty able to add new nucleotides onto the 3' end of the growing strand (replication occurs in the 5' to 3' direction)

Question 33

In what direction does DNA replication occur?

Answer 33

In the 5' to 3' direction

Question 34

What fragments are formed on the lagging strand and how are they koint together?

Answer 34

Okazaki fragments which are joined together by DNA ligase

Question 35

What are the 2 stages of cellular division?

Answer 35

Prometaphase Metaphase

Question 36

When are chromosomes most compacted?

Answer 36

During metaphase where the chromatin fibres are folded into multiple loops and coils (1000 times more compact than other stages)

Question 37

What percentage of bases in people are the same?

Answer 37

99.9%

Question 38

Roughly how many genes are there in the genome?

Answer 38

22000

Question 39

What percentage of the genome codes for proteins?

Answer 39

\<2%

Question 40

What are exons?

Answer 40

Coding region

Question 41

What are introns?

Answer 41

Non-coding regions

Question 42

What is a codon?

Answer 42

Set of 3 bases

Question 43

What does each codon specify?

Answer 43

A particular amino acid

Question 44

How many different codons and amino acids are there (found in proteins)?

Answer 44

64 codons 20 amino acids

Question 45

What occurs due to there being 64 codons but only 20 amino acids?

Answer 45

Degeneracy

Question 46

What is degeneracy?

Answer 46

More than one codon codes for the same amino acid

Question 47

What are codons that code for the same amino acid refered to as?

Answer 47

Synonyms which tend to be very similar

Question 48

Where do variations of synonyms tend to occur?

Answer 48

The third base

Question 49

What does degeneracy minimise?

Answer 49

The effect of genetic mutations as the change is less likely to change which protein is coded

Question 50

What do all polypeptides begin with?

Answer 50

Methionine (initiation codon)

Question 51

What is methionine?

Answer 51

Initiation codon

Question 52

What often happens to methionine (initaiton codon)?

Answer 52

Removed at a later stage

Question 53

What can single point mutations cause?

Answer 53

A dysfunctional protein

Question 54

What is an example of a single point mutation causing a dysfunctional protein?

Answer 54

Mutated haemoglobin gene causing sickle cell anaemia

Question 55

What is the major role of RNA?

Answer 55

To participate in protein synthesis

Question 56

What are the 3 kinds of RNA?

Answer 56

Messanger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)

Question 57

What is mRNA?

Answer 57

Transcribed from DNA and carries genetic information for protein synthesis

Question 58

How can the same gene produce many different proteins?

Answer 58

Due to splicing which occurs after the synthesis of mRNA

Question 59

What is alternative splicing?

Answer 59

Process where exons of the RNA prdouced by transcription of a gene (primary gene transcript) are reconnected in multiple ways during RNA splicing

Question 60

What is the RNA strand before splicing occurs called?

Answer 60

Primary gene transcript

Question 61

What determines the reading frame of the RNA sequence?

Answer 61

Initiation codon

Question 62

What is the space between the start and stop codon called?

Answer 62

Open reading frame

Question 63

Where does transcription, alternative splicing, protein synthesis and post translational modifications take place?

Answer 63

Transcription in the nucleolus Alternative splicing in the nucleus Protein synthesis in the ribosome Post translational modifications in the endoplasmic reticulum

Question 64

What is tRNA?

Answer 64

Major role is to translate mRNA sequence into amino acid sequence

Question 65

What are the complimentary 3 bases on tRNA refered to as?

Answer 65

Anticodon

Question 66

What is rRNA?

Answer 66

Component of ribosomes, are produced in the nucleus and transported to the cytoplasm where they form a ribosome

Question 67

What is a polysome?

Answer 67

What is produced when several ribosomes can trasnlate mRNA at one time

Question 68

What base is present in mRNA instead of what?

Answer 68

Uracil is present instead of thymine