Topic 1.3 Biological molecules 2 Flashcards
What are nucleotides?
molecules with 3 parts, a 5-carbon pentose sugar, nitrogen-containing base and a phosphate group (joined by condensation reactions)
What is ATP, adenosine triphosphate?
a nucleotide that acts as the universal energy supply molecule in cells. it is made up of an adenosine base, pentose sugar ribose and 3 phosphate groups
What are purine bases?
bases found in nucleotides which have 2 nitrogen-containing rings
What are pyrimidine bases?
bases found in nucleotides which has 1 nitrogen-containing ring
What is adenine and guanine?
purine bases found in DNA and RNA
What is cystosine?
pyrimidine base found in DNA and RNA
What is thymine?
pyrimidine base found in DNA
What is uracil?
pyrimidine base found in RNA, replaces thymine
What is the function of ATPase?
an enzyme that catalyses the formation and breakdown of ATP, depending on conditions
What is ADP, adenosine diphosphate?
a nucleotide formed when ATP loses a phosphate group and provides energy to drive reactions in the cell
Define redox reactions
reactions in which one reactant loses electrons
oxidation) and another gains electrons (reduction
Define nucleic acids
polymers made up of many nucleotide monomer units that carry all the information needed to form new cells
What is a phosphodiester bond?
the bond formed between the phosphate group of one nucleotide and the sugar of the next nucleotide in a condensation reaction. DNA ligase catalyses their formation in DNA replication
Define a genome?
the entire genetic material of a organism
Which base does adenine pair with?
A,T thymine
Which base does guanine pair with?
C,G cytosine
What bond forms between 2 strands of DNA to form the double helix structure?
hydrogen bonds
How many hydrogen bonds are between C and G?
3 bonds
How many hydrogen bonds are between A and T?
2 bonds
What are the names are the 2 strands?
5’ and 3’ according to which carbon the phosphate group is attached to in the first nucleotide of the chain
How does DNA replicate?
copies itself exactly
How was DNA replication tested?
though experiments on semi-conservative and conservative replication
What is conservative replication?
where the double helix remains intact and new stands form on the outside
What is semiconservative repliaction?
where the double helix unzips and each strand replicates to produce a second, new strand
What does DNA helicase do?
an enzyme involved in DNA replication that unzips two strands on the DNA molecule
What does DNA polymerase do?
an enzyme involved in DNA replication that lines up and catalyses the linking up of the nucleotides along the template strand
What is the function of DNA ligase?
an enzyme involved in DNA replication that catalyses the formation of phosphodiester bonds between the 2 strands of DNA
Describe translation
the process by which proteins are produced, via RNA, using the genetic code found in the DNA. takes place on the ribosomes
What are ribosomes?
the site of protein synthesis in the cell
Define the triplet code
the code of 3 bases and is the basis of the genetic information in DNA
What is a gene?
a sequence of bases on a DNA molecule. contains coding for a sequence of amino acids in a polypeptide chain that affect a characteristic in the phenotype of the organism
Define a codon
a sequence of 3 bases in DNA or mRNA
What’s a complementary strand?
the strand of RNA formed that complements the DNA acting as the coding strand
What type of mutation causes sickle cell disease?
substitution
What is an anticodon?
a sequence of 3 bases on tRNA that are complementary to the mRNA codon
What is a mutagen and examples?
anything that increases the rate of a mutation e.g. smoking, x-rays
Explain the importance of DNA replication during the development of a zygote into a blastocyst
- zygote divided several times by mitosis
- to make identical copies of the DNA/chromatids
- so that all the cells will be diploid
- so that when the mitochondria divide they will have a copy of the DNA
