Nucleic Acids Flashcards
What are the two types of nucleic acids?
DNA and RNA
What is the full meaning and DNA and RNA
deoxyribonucleic acid
ribonucleic acid
what does deoxy mean?
without oxygen
What is the function of DNA and RNA?
They both are important information carrying molecules
What is the function of DNA?
Codes for the sequence of amino acids in the primary structure of a protein
What is the function of RNA?
Copies and transfer genetic information from DNA to ribosomes
Give the nucleotide structure? And what is a nucleotide?
• A pentose (either deoxyribose/ ribose), a nitrogen-containing organic base, and a phosphate group
• A monomer of a polynucleotide
Draw a nucleotide
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Draw a ribose sugar
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What are the components of a DNA nucleotide?
Deoxyribose, a phosphate group, and one of the organic bases: adenine, thymine, guanine, and cytosine.
What are the components of an RNA nucleotide?
ribose, a phosphate group, and one of the organic bases: adenine, guanine, cytosine, and uracil.
What is the bond between each nucleotide? And how is it formed
Phosphodiester bond: Strong covalent bonds formed via a condemnation reaction
Describe the structure of a DNA molecule
A DNA molecule is a double helix with two polynucleotide chains/strands held together by hydrogen bonds between specific complimentary base pairs
Describe the structure of an RNA molecule
A short, single-stranded polynucleotide chain
Give the 3 types of RNA
messenger RNA
transfer RNA
ribosomal RNA
Which types of RNA are involved in protein synthesis?
messenger RNA and transfer RNA
What is the function of ribosomal RNA
forms ribosomes by combining with a protein
What is a codon
What Every 3 bases in the sequence code for a specific amino acid is called
What virus contains RNA
Retro viruses
What is the function tRNA
• Transfers specific amino acid to the ribosome to create a polypeptide chain
• attaches to a specific amino acid to the mRNA and this is controlled by complimentary base pairing
How are codons and anticodons linked together?
through hydrogen bonds between complimentary base pairs
What is mRNA? And give its function
•Copy of one gene from DNA
• Created in the nucleus
• Shorter so it can leave the nucleus, the length of one gene
• Short lived as it is only needed temporarily to create protein and so that enzymes won’t hydrolyse it
• To leave the nucleus and carry the copy of the genetic code of one gene to a ribosome in the cytoplasm
Where does translation occur?
In the cytoplasm
What is a gene?
A section of DNA that codes for proteins
Where is DNA enclosed in?
within a nucleus
What is the shape of tRNA
A clover shape, held together by hydrogen bonds
Multiple phosphodiester bonds form what? And what is this bond made up of?
• A negative sugar-phosphate backbone
• Strong covalent bonds between the sugar (deoxyribose) and a phosphate group
Which bases will always be equal to each other?
Adenine will always be equal to thymine and guanine will always be equal to cytosine
What do DNA molecules wrap around and why? What makes them wrap around?
They wrap around histone proteins because they are positively charged.
Phosphate group makes them wrap around histone proteins
Name the people that discovered the structure of DNA
Watson, Crick and Rosalind Franklin
What cells are genetically identical
Daughter cells
How is the structure of DNA linked to its function (mark scheme answer)
8 marks
• Sugar-phosphate backbone and double helix provides stability and protects hydrogen bonds
• Long/ large molecules so it can store lots of information
• It’s helical/coiled so it can compact
• Base sequence allows information to be stored/ codes for amino acids
• Double stranded so replication can occur semi-conservatively using one strand as a template
• Complimentary base pairing so identical copies can be made
• Weak hydrogen bonds for the unzipping of two strands in a double helix during replication
• Many hydrogen bonds so it’s stable
What is a polynucleotide?
A polymer made up of nucleotides
What is semi- conservative replication
During DNA replication, a double stranded DNA molecule separate, and each strand is used as a template for the synthesis of a new strand. This results in the formation of two identical copies of the original double stranded molecule.
What does semi-conservative ensure?
•It ensures the genetic continuity between generations of cells
• To ensure that all DNA must replicate to produce a copy for a new cell
Describe the process of semi-conservative replication of DNA
STEP1: DNA helipads breaks down the hydrogen bonds between complimentary base pairs between the two strands which cause the double helix to unwinds
STEP2: Each separated parental DNA strand acts as a template. Free floating DNA nucleotides within the nucleus are attracted to their complimentary base pairs on the template strands of the parental DNA
STEP3: The adjacent nucleotides are joined together to form a phosphodiester bond via a condensation reaction. DNA polymerase catalysed the joining together in f adjacent nucleotides
STEP 4: The two sets of Daughter DNA (name given to a new DNA molecule) Contains one strand in f the parental (original) DNA and one newly synthesised strand
What scientists proved the evidence of semi-conservative replication
Stahl and meselson
Why is it called semi-conservative replication?
Half of the strands in each new DNA molecule are from the original DNA molecule
What did meselson And stahl use for their experiment? And what did they hypothesise
• They used two isotopes of nitrogen: the lighter nitrogen N14 and heavier nitrogen N15 to make new DNA nucleotides
• Semi-conservative replication and conservative replication
Different DNA is as a result of what?
Different genes
Different DNA will have different what?
Base sequence
What type of polymers are DNA and RNA
Polymers of neuclotides
How many bonds form between adenine and thymine and how many bonds form between guanine and cytosine
• 2 bonds between thymine and adenine
• 3 bonds between guanine and cytosine
How many differences are there between DNA and RNA
2 because there are differences in their monomers and in their polymers
Where is tRNA found and give its structure
• Found in the cytoplasm
• Single stranded
Why can’t DNA leave the nucleus
• It’s too large to leave
• At risk of being damaged by enzymes therefore destroying the genetic doe permanently
Which 3 people discover the structure of DNA
Watson and Crick and Rosalind Franklin
Describe the investigation of semi-conservative replication
• Bacteria grown in a medium containing N14, light nitrogen will have DNA which only contains this isotope
• Bacteria grown in a medium containing N15 heavy nitrogen will have DNA which only contains this isotope
• DNA samples can be spin in a centrifuge to confirm density
Describe the process of investigating semi-conservative replication
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