Biological Molocules 2 Flashcards
What makes up a nucleotide?
5-carbon pentose sugar
Nitrogen-containing base
Phosphate group
What is the pentose sugar in RNA?
Ribose
What is the pentose sugar in DNA?
Deoxyribose
What is the difference between a purine and a pyramidine?
A purine has two nitrogen-containing rings and pyramiding has one
What are the most common purines?
Adenine
Guanine
What are the most common pyramidines?
Cytocine
Thymine (DNA)
Uracil (RNA)
Do nucleotides carry a positive or negative charge?
Negative
What reaction joins the components of a nucleotide?
Condensation reaction
What is ATP?
The universal energy supplier in cells
How does the structure of ATP help it carry out it’s function?
The third phosphate bond in the molocule is broken in hydroysis catalysed by ATPase to produce ADP which makes energy
What catalyses the hydrolysis of ATP molocules?
ATPase
What is the function of nucleic acids?
They carry the information needed to form new cells when copied onto mRNA. It stores genetic information in chromasomes
What are nucleic acids?
Chains of nucleotides linked together by condensation reactions that produce phosphodiester bonds between the sugar on one nucleotide and the phosphate group on the next.
What bond is in the sugr-phosphate backbone?
Phosphodiester
What is the difference between DNA and RNA?
RNA: Single stranded and can fold into complex shapes held together by hydrogen bonds
DNA: Double helix with the sugar-phosphate backbone on the outside and the bases inside held by hydrogen bonds
What bond holds the bases of the two DNA strands together?
Hydrogen
How many hydrogen bonds are there between bases C and G?
three
How many hydrogen bonds are there between bases A and T?
two
Why are the strands called 3 prime and 5 prime?
Depends on which carbon atom in the pentose sugar that the first phosphate group in the chain is attatched to
What was the conservative model of replication?
The original double helix stays intact and the new helix is made up of entirely new material
What is the semi-conservative model of replication?
The DNA is unzipped with new nucleotides lining up along each strand so each new helix had half of the original material and half of the new material
How does DNA replicate?
Semi-conservatively
DNA helicase unzips the strands
Free nucleotides join to the exposed bases to form matching pairs
DNA polymerase links the nucleotides along the template strand
DNA ligase catalyses the formation of phosphodiester bonds
What role does DNA helicase play in replication?
It unzips the two strands of DNA along the hydrogen bonds
What role does DNA polymerase play in replication?
Catalyses the linking up of nucleotides along the template strand, creating new hydrogen bonds
What is the role of DNA ligase in replication?
It catalyses the formation of phosphodiester bonds along the sugar-phosphate backbone
How is DNA a triplet code?
A sequance of three bases code for each amino acid which are arranged together in a polypeptide chain
What is a codon?
A sequance of three bases in DNA or RNA
What does T/U bond with?
A
What does C bond with?
G
Why is it a good thing that DNA is non-overlapping?
A point mutation will only affect a single amino acid
What are the main functions of RNA in protein synthesis?
To carry instructions for a polypeptide from the DNA in the nucleus to the ribosomes where proteins are made
It picks up specific amino acids from the protoplasm and carries them to the surface of the ribosomes
It makes up most of the ribsomes themselves
Where is mRNA formed?
The nucleus
What is the antisense strand?
mRNA
What is the sense strand?
DNA
How is mRNA created?
The DNA unravels by RNA-directed DNA polymerase and complimentry bases line up alongside the sense strand. Phosphodiester bonds are catalysed along the backbone of the mRNA by RNA polymerase
How is the mRNA able to pass through the nuclear envelope?
It’s small enough to pass through the pores
What is the purpose of mRNA?
To carry instructions for a polypeptide from the DNA in the nucleus to the ribosomes where proteins are made
What is the purpose of tRNA?
It picks up specific amino acids from the protoplasm and carries them to the surface of the ribosomes
What is the purpose of rRNA?
It makes up most of the ribsomes themselves
Where is tRNA found?
The cytoplasm
What is an anticodon?
The sequance of three bases found on tRNA
How is a polypeptide created?
The mRNA travels to the ribosome where tRNA with the complimentry anticodon binds. The amino acids on the other end of the tRNA join together as the mRNA travels through the ribosome, peptide bonds forming between them.
Where is rRNA found?
It is made in the nucleus but makes up 50% of the ribosomes.
What is a mutation?
A permenant change in the DNA of an organism
How can the body deal with mutations?
It has specific restriction enzymes to cut out or repair broken strands of DNA
What are point mutations?
Only one nucleotide is miscopied during transcription
What are some different types of point mutations?
Deletion
Substitution
Insertation
What is a chromasomal mutation
Changes of the position of genes in chromasomes
What is a whole-chromasome mutation?
An entire chromasome is either lost or gained during meiosis
