Nucleic acids and ATP Flashcards
Name the pentose sugars in DNA & RNA
Deoxyribose
Ribose
State the role of DNA in living cells
Base sequence of genes codes for functional RNA& amino acid sequence for polypeptides
Genetic information determines inherited characteristics = influences structure and functions of organisms
State the role of mRna (Type of RNA)
Complementary sequence to 1 gene from DNA with introns (non coding regions) spliced out. Codons can be translated into a polypeptide by ribosomes
State the role of rRNA (type of RNA)
Component of ribosomes (along with proteins)
State the role of tRNA( type of rna)
Supplies complementary amino acid to mRNA codons during translation
Describe the structure of DNA
Double helix of 2 polynucleotide strands (Deoxyribose)
H-bonds between complementary purine and pyrimidine base pairs in opposite strands:
Adrenaline(A) +Thymine(T)
Guanine(G) + Cytosine(C)
Which bases are purine and which are pyrimdine
A&G = 2 ring purine bases
T & C & U= 1- ring pyrimdine bases
Name the complementary base pairs in DNA
2 H-bond between
Adrenaline(A) + Thymine (T)
3 H-bonds between Guanine(G)+Cytosine(C)
Name the complementary base pairs in RNA
2 H bonds between
Adrenaline (A) + Uracil (U)
3 H bonds between
Guanine(G) + Cytosine (C)
Name the complementary base pairs in RNA
2 H bonds between
Adrenaline (A) + Uracil (U)
3 H bonds between
Guanine(G) + Cytosine (C)
Relate the structure of DNA to its functions
Sugar-phosphate backbone& many H bonds provide stability
Long molecules stored lots of information
Helix is compact for storage in nucleus
Base sequence of triplets codes for amino acids
Double stranded for semi conservative replication
Complementary bare pairing for accurate replication
Weak H-bonds break so strands separate for replication
Describe the structure of messenger RNA (mRNA)
Long ribose polynucleotide (but shorter than DNA)
Contains Uracil instead of thymine
Single stranded and linear (no complementary base pairing)
Codon sequence is complementary to exons of 1 gene from 1 DNA strand
Relate the structure of messenger RNA to its functions
Breaks down quickly so no excess polypeptides forms
Ribosomes can move along strand & tRNA can bind to exposed bases
Can be translated into specific polypeptide by ribosomes
Describe the structure of transfer RNA(tRNA)
Single strand of about 80 nucleotides
Folded into clover shape
Anticodon on one end ,amino acid binding site on the other
anticodon binds to complementary mRNA codon
Amino acid corresponds to anticodon
Order DNA, mRNA and tRNA according to increasing length
tRNA mRNA DNA
why did scientists initially doubt that DNA carried genetic code
Chemically simple molecule with few components
Why is DNA replication described as semi conservative
Strands from original DNA molecule act as a template
New DNA molecule contains 1 old strand and one new strand
Outline the process of semi conservative DNA replication
Dna helicase breaks h bond between pairs
Each strand acts as a a template
Free nucleotides from nuclear sap attattch to exposed bases by compmetary base pairing
DNA polymerase catalyses condensation reactions that join adjacent nucleotides on new strand
H bond reforms
Describe the Meselson-Stahl experiment
Bacteria were grown in a medium containing heavy isotope N15 for many generations
Some bacteria were moved to a medium containing light isotope N14.Samples were extracted after 1&2 cycles of DNA replication
Centrifugation formed a pellet. Heavier DNA (bases from N15) settled closer to the bottom of the tube
Explain the role of ATP in cells
ATP hydrolyse catalyses ATP—> ADP + Pi
Energy released is coupled to metabolic reaction
Phosphate group phosphorlates compounds to make them more reactive
HOW is ATP resynthesysed in cells
ATP synthase catalyses condensation reaction between ADP & Pi
During photosynthesis & respiration
Explain why ATP is suitable as the energy currency of cells
High energy binds between phosphate groups
Small amounts of energy released at a time = less energy wasted as heat
Single step hydrolysis=energy available quickly
Readily resynthesised
Describe the basic function of DNA in all living cells
Holds genetic information which codes for polypeptides
Describe the basic function of RNA in all living cells
Transfers genetic information from DNA to ribosomes
Name the two types of molecule from which a ribosome is made
RNA and proteins
DRaw and label a dna molecule and an RNA nucelotide
pg 15 in bio with olivia
Describe the differnces between a DNA nucelotide and an RNA Nucelotide
DNA nucelotide is deoxyribose whilst in RNA it is rbose
The base for DNA nucelotide is thymine whilst the base for RNA is Uracil
Describe how nucelotides join together to form polynucelotides
Condensation reactions,removing water between phosphate group of one nucleotide and deoxyribose/ribose of another forming phospodiester bionds
Why did many scientists intially doubt that DNA carried the genetic code
The relative simplictiy of DNA- chemically simple molecule with few componenets
Describe the structure of DNA
- Polymer of nucleotides(polynuxelotide)
- Each nucelotide(Nltd) formed from deoxyribose, a phosphate group and a nitrogen containing organic base
- Phosphodiester bonds join adjacent nltds
- 2 polynltd chains held together by hydrogen bonds between specific complemetary base pairs- adenine/thyminand cytosine/guanine
- Double helix
Describe the strcuture of MRNA
- Polymer of nltds (polynltd)
- each nltd formed from ribose or a phosphate group and a nitrogen containing organic base
- Bases-Uracil adenine cytosine and guanine
- Phosphodiester bonds join adjacent nltds
- Single helix
nltd=nucelotide
plural with a s at the end
Compare and contrast the strcuture of DNA and mRNA
- The pentose sugar in DNA is Deoxyribose whilst in mRNA it is ribose
- DNA has the base Thymine mRNA is Uracil
- DNA is double helix mRNA is single helix
- Long(many nltds) in DNA whilst in mRNA it is short (fewer nltds)
- DNA has hydrpgen bonds/base pairing whilst in mRNA there are none
nltd=nucelotide
Suggest how the structure of DNA relates to its function
- Two strands-both can act as templates for semi conservative replication
- Hydrogen bonds between basesare weak-strands can be separated for replication
- Complemmntary base pairing-accruate replkcation
- Many strong bonds between bases- stable/strong molecule
- Double helix with sugar phosphate backbone-protects bases/ hydrogen bonds
- long molecule-stores ots of genetoc information that codes for polypeptides
- double helix)coiled)-compact
Suggest how you can use incomplete informatoion about the frrquency of bases on DNA starnds to find the frequency of othe rbases
- % of adenine in strand 1= % of thymine in strand 2 (and vice versa)
- % of guaninein strand 1 = % of cytosine in strand 2 (and vice versa)
because of pecifc ciomplemnatry base pairing between 2 strands
