Storing and Using Genetic Information Flashcards
<p>What is a phenotype?</p>
<p>Physical manifestation of genotype</p>
<p>What is a genotype?</p>
<p>All of the genes in our DNA, even the ones that are not expressed</p>
<p>Why are proteins functionally different?</p>
<p>Due to their different structures</p>
<p>What does the structure of a protein depend on?</p>
<p>The primary structure (sequence of amino acids)</p>
<p>What is DNA?</p>
<p>A chain of nucleotide monomers that contains all of our genetic information</p>
<p>What does each nucleotide contain?</p>
<p>Sugar</p>
<p>Base</p>
<p>Phosphate group</p>
<p>What structure does DNA form?</p>
<p>Double helix</p>
<p>How many bases is there per turn of the helix?</p>
<p>10</p>
<p>How do polypeptide chains of DNA run to each other?</p>
<p>Antiparralel to one another</p>
<p>How are the groves in DNA described?</p>
<p>Major and minor groves which is important for the interaction of proteins</p>
<p>What is the pairing of bases called?</p>
<p>Compliment base pairing</p>
<p>What bases pair with what in DNA?</p>
<p>Thymine paires with adenine</p>
<p>Guanine pairs with cytosine</p>
<p>What does compliment base pairing happen?</p>
<p>Due to the structures of the bases:</p>
<p>Thymine pairs with ademine due to both forming 2 hydrogen bonds</p>
<p>Guanine pairs with cytosine due to both forming 3 hydrogen bonds</p>
<p>What bases form 3 hydrogen bonds with each other?</p>
<p>Cytosine and guanine</p>
<p>What bases form 2 hydrogen bonds with each other?</p>
<p>Thymine and adenine</p>
<p>What is the site of a cells genetic information (DNA)?</p>
<p>Nucleus</p>
<p>Where does the first step of protein production take place and what is this?</p>
<p>DNA replicaiton which takes place in the nucleus</p>
<p>What does each nucleus contain?</p>
<p>A nucleolus which can take up to 25% of its volume and is where transciption and assemble of rRNA takes place</p>
<p>Where does transcription and assemble of rRNA take place?</p>
<p>Nucleolus</p>
<p>What is DNA packaged into?</p>
<p>Thread like structures called chromosomes</p>
<p>When are chromosomes visible?</p>
<p>During cell division</p>
<p>What is a chromosome?</p>
<p>Single piece of DNA containing many genes, regulatory elements and other nucleotide sequences</p>
<p>How many chromosomes does a human have?</p>
<p>46</p>
<p>What can the structure of chromosomes be described as?</p>
<p>Highly ordered to contain vast amounts of DNA</p>
What is the process of packaging chromosomes?
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
What is chromatin?
Mixture of DNA, proteins and RNA thay packages DNA within the nucleus
What are the 2 forms of chromatin?
Heterochromatin (condensed)
Euchromatin (extended)
What must the chromatin do for transcription and replication to occur?
Open up to allow enzymes to access the DNA template
What are the 2 mechanisms for opening up chromatin to allow replication or transcription to occur?
Histones can be enzymatically modified
Histones can be displaced by chromatin remodelling complexes
What should be noted about both processes of opening up chromatin?
They are reversible
What does it mean that DNA replication is semi conservative?
Half of each new molecule is old DNA and half is new DNA
What does it mean that DNA replication is bi-directional?
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)
In what direction does DNA replication occur?
In the 5' to 3' direction
What fragments are formed on the lagging strand and how are they koint together?
Okazaki fragments which are joined together by DNA ligase
What are the 2 stages of cellular division?
Prometaphase
Metaphase
When are chromosomes most compacted?
During metaphase where the chromatin fibres are folded into multiple loops and coils (1000 times more compact than other stages)
What percentage of bases in people are the same?
99.9%
Roughly how many genes are there in the genome?
22000
What percentage of the genome codes for proteins?
<2%
What are exons?
Coding region
What are introns?
Non-coding regions
What is a codon?
Set of 3 bases
What does each codon specify?
A particular amino acid
How many different codons and amino acids are there (found in proteins)?
64 codons
20 amino acids
What occurs due to there being 64 codons but only 20 amino acids?
Degeneracy
What is degeneracy?
More than one codon codes for the same amino acid
What are codons that code for the same amino acid refered to as?
Synonyms which tend to be very similar
Where do variations of synonyms tend to occur?
The third base
What does degeneracy minimise?
The effect of genetic mutations as the change is less likely to change which protein is coded
What do all polypeptides begin with?
Methionine (initiation codon)
What is methionine?
Initiation codon
What often happens to methionine (initaiton codon)?
Removed at a later stage
What can single point mutations cause?
A dysfunctional protein
What is an example of a single point mutation causing a dysfunctional protein?
Mutated haemoglobin gene causing sickle cell anaemia
What is the major role of RNA?
To participate in protein synthesis
What are the 3 kinds of RNA?
Messanger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
What is mRNA?
Transcribed from DNA and carries genetic information for protein synthesis
How can the same gene produce many different proteins?
Due to splicing which occurs after the synthesis of mRNA
What is alternative splicing?
Process where exons of the RNA prdouced by transcription of a gene (primary gene transcript) are reconnected in multiple ways during RNA splicing
What is the RNA strand before splicing occurs called?
Primary gene transcript
What determines the reading frame of the RNA sequence?
Initiation codon
What is the space between the start and stop codon called?
Open reading frame
Where does transcription, alternative splicing, protein synthesis and post translational modifications take place?
Transcription in the nucleolus
Alternative splicing in the nucleus
Protein synthesis in the ribosome
Post translational modifications in the endoplasmic reticulum
What is tRNA?
Major role is to translate mRNA sequence into amino acid sequence
What are the complimentary 3 bases on tRNA refered to as?
Anticodon
What is rRNA?
Component of ribosomes, are produced in the nucleus and transported to the cytoplasm where they form a ribosome
What is a polysome?
What is produced when several ribosomes can trasnlate mRNA at one time
What base is present in mRNA instead of what?
Uracil is present instead of thymine
