Chapter 6: Nucleic acids and protein synthesis Flashcards
What are the main parts of a nucleotide?
- a 5-carbon sugar
- a nitrogen-containing base
- an inorganic phosphate group
how are the main components of the nucleotide linked together?
A covalent bond that is a phosphodiester bond
what is the type of sugar in a nucleotide? Give two examples of it as seen in RNA and DNA
nucleotides have pentoses. in RNA, the pentose is Ribose and in DNA is is deoxyribose.
What is the difference between ribose and deoxyribose?
The difference between the sugars is the presence of the hydroxyl group on the 2’ carbon of the ribose and its absence on the 2’ carbon of the deoxyribose.
name the organic bases that occur in DNA and RNA.
Adenin, Thymine, Cytasine, Guanine and Uracil.
The Organic bases come in two main categories. Name them, and state their differences.
Purines and Pyrimidines.
Purines have a double ring structure and pyrimidine only have a ring structure.
Purines include Adenine and Guanine while Pyrimidines include Cytosine, Thymine and Uracil
What is ATP?
Adenine triphosphate is a phosphorylated nucleotide, Adenosine joined to three phosphate groups.
What is Adenosine?
It is Adenine bonded to ribose
What is RNA and DNA?
Ribonucleic acid and Deoxyribonucleic acid are both polynucleotides
What are polynucleotides?
The are polysacchrides made from the bonding of many nucleotides.
What is the strcture of RNA?
RNA is a single-stranded polynucleotide. Each nucleotide of RNA will consist of a phosphate group, ribose and an organic group. The Base of RNA are adenine, uracil, cytosine and guanine.
What is the structure of DNA?
DNA is a double-stranded polynucleotide consisting of two complementary polynucleotides strands held together by hydrogen bonds.
What are complemantary base pairs?
In DNA, adenine will always pair with thymine while guanine always pairs with cytosine. A purine will always pair with a pyrimidine. Adenine bonds with thymine with two hydrgen bonds and guanine and cytosine pair with three hydroen bonds.
the DNA strands are seid to be antiparallel?
They run in opposite directions. one from carbon 3’ to 5’ and the other from carbon 5’ to 3’
What do you call the twisting of the DNA strand?
A double Helix
Outline the semi conservative replication of DNA
The two strands of DNA separate, by breaking the ydroge bonds between complementary base pairs. Each strand of DNA acts as a template for the synthesis of a new, complementary DNAstrand alongside it.Complementary bases to those in the strand of DNA are joined together to form a strand of RNA.
During which phase during the cell cycle does semi-conservative replication.
Semi conservative replication happens during the S-phase
Name the enzymes involved in semi-conservative replication
DNA Helicase separates the two strands of the DNA double helix, while DNA polymerase joins the two nucleotides to form the new, complementary srandsof DNA
What is a gene?
Is the specific part of the DNA that codes for a particular polypeptide
what si the role of DNA?
It contains genetic information and the sequence of bases which will specify the sequence that amino acids will join together to form polypeptide strands.
What is a codon?
A codon is a squence of 3 bases.
What doe sit mean when the genetic code is said to degenerate?
with 4 bases, there are 64 possible codons, which is more than enough to code for the required 20 amino acids. Degenaration happens because many codons cans till coe for the same amino acid.
What are the two stages of protein synthesis?
- DNA transciption
2. DNA translation
what is DNA transcription?
It is when a molecule of mRNA is synthesized. is uses the complementary base pairing of DNA, using I as a template. DNA polymerase unzips the DNA and the complimentary bases pair up as the DNA polymerase slides along the gene. then an mRNA molecule is formed.
what is dna translation?
it is the process where the sequence of bases on the mRNA molecule is used to specify the order in which amino acids will be joined together to form a polypeptide
what is the relationship between robosomes and the mRNA?
In the eukaryotic cell, mRNA leaves the nucleus and attaches to a ribosome in the cytoplasm. Ribosomes are the sited of the protein synthesis, and is where the genetic code is the mRNA molecule translated into appropriate sequence of amino acid.
What is the role of the tRNA molecule?
it contains the anticodon that is complementary tt the codon on the mRNA. this allows the protein to be synthesized as the individual amino acids are brought along with the tRNA molecule.
describe the sysnthesis of a polypeptide after the first amino acid has been brought.
The ribosome will move along the mRNA. as this happens tRNA will bring the specific anticodons as specified by the codons on mRNA. the amino acids will join by the formation of peptide bonds to form the polypeptide chain. this continues until the stop codon is reached.
What is a mutation and what are its effects?
A mutation is a chnage in the DNA. it may effect the polypeptide codedn by that specific gene.
Describe the effect of a mutation on heamoglobin.
a mutation occurs that affects the formation of haemoglobin. the codon that should be CTT is CAT, and this results in the polypeptide having Glutamic acids instead of Valine.
what is the effect to heamoglobin when glutamic acid is replaced with valine?
It significanlty changes the structures and the properties.
What alleles does a perosn need to have to have sicle cell anemia?
HbsHbs. They should be homozygous to the recessive allele.
