Nucleic Acids & Genetic Information Flashcards
State the process of producing mRNA from DNA
Transcription
State the process of producing protein from mRNA
Translation
State the process of producing DNA from mRNA
Retrotranscription
Both DNA and RNA consist of polymers of monomers. What are these monomers called?
Nucleotides
What do nucleotides consist of?
A phosphate group
A pentose sugar
A nitrogenous base
Nucleoside + Phosphate = ________?
Nucleotide
How many rings are in a Purine?
2
How many rings are in a Pyrimidine?
1
Give all the examples of Purine bases
Adenine, Guanine
Give all the examples of Pyrimidine bases
Cytosine, Uracil and Thymine
Give 3 examples of other roles of nucleotides (apart from carrying the genetic code) with examples
Energy carrier i.e. ATP
Signalling i.e. cAMP, cGMP
Enzyme cofactors i.e. CoA, FMN, FAD, NAD
Who devised the “Double Helix” structure and when?
Watson & Crick, 1953
DNA has directionality, what direction is this?
5’ to 3’
How many hydrogen bonds pair a C base with a G base in the double helix?
3
How many hydrogen bonds pair with an A base and a T base in the double helix?
2
What is the name of bonds which bind phosphate groups to sugar groups in DNA?
Phosphodiester bonds
What is a phosphodiester bond?
A bond which links phosphate and sugar groups in the backbone of DNA
The human genome has roughly how many base pairs?
3 billion
Compare how Nuclear DNA is structured with respect to Mitochondrial DNA
Nuclear DNA is linear and packaged into chromosomes, whilst MtDNA is circular
What is the basic fundamental unit of chromatin called? What is it comprised of?
A nucleosome, which is comprised of DNA packaged around 8 histones
Nucleosomes can be described as beads on a string. What is the string’s technical name in this instance?
DNA linker region
What is the difference between “euchromatin” and “heterochromatin”?
Euchromatin - lightly packed chromatin
Heterochromatin - densely packed chromatin
Describe what the chromosomal scaffold is..
The chromosomal scaffold is described as a chromatin fibre associated with non-histone proteins
What is a centromere?
The centromere is the part of a chromosome that links sister chromatids
What is a chromatid?
One copy of the duplicated chromosome
What is a telomere? What is its function?
A series of repetitive nucleotide sequences at the ends of chromosomes. They protect chromosomes from deterioration during replication
What is the q arm of a chromosome?
The long arm
What is the p arm of a chromosome?
The short arm
Each somatic human cell contains how many chromosomes?
46
How many different autosomal chromosome pairs are there
22
What is an allosome?
A sex chromosome
What are the two allosomes?
X and Y chromosomes
How many homologous chromosome pairs does a human have?
23
What is the “karyotype” of a chromosome?
The karyotype is the number and appearance of chromosomes in a eukaryotic cell
What is “aneuploidy”?
An abnormal number of chromosomes in a cell
What is “trisomy”?
A type of aneuploidy, whereby there is an extra copy of a chromosome
Give three examples of Trisomy conditions affecting autosomal chromosomes
Trisomy 21 - Down’s Syndrome
Trisomy 18 - Edwards Syndrome
Trisomy 13 - Patau Syndrome
Give two examples of Trisomy conditions affecting allosomal chromosomes
XXX - Triple X syndrome
XXY - Klinefelter syndrome
What is “genomic medicine”?
A medical discipline that involves genomic information about an individual as part of their clinical care
How long is a typical cell cycle length in mammals?
12-24 hours
What is the G0 phase of a cell cycle?
The resting phase, where a cell has not started to divide yet. Once it gets a signal, it can move into the G1 phase
What are the three sub-phases of Interphase?
G1, S, G2
How long does G1 phase last for and what happens here?
18-30 hours
Cell increases protein synthesis and metabolic activity
How long does S phase last for and what happens here?
18-20 hours
Chromosomes containing DNA are duplicated
How long does G2 phase last for and what happens here?
2-10 hours
Cell prepares for mitosis and the splitting of the cell
How long does M phase last for and briefly state what happens here?
30-60 mins
Cell produces two daughter cells
State the subphases of mitosis
Prophase (Prometaphase) Metaphase Anaphase Telophase
Describe the structure of the mitotic spindle
The mitotic spindle is made up of microtubules and originates from the two centrosomes which migrate to opposite ends of the cell
The mictotubules of the mitotic spindle attach to which structure on a chrosome?
Kinetochore
What occurs during Prophase?
- The chromosomes condense
- Nucleoli disperses
- Centrosomes seperate and form a mitotic spindle
What occurs during Prometaphase?
- Nuclear envelope fragments
- Spindles attach to centromeres
- Chromosomes begin to move towards thecell centre
What occurs during Metaphase
Chromosome alignment at the metaphase plate
What occurs during Anaphase
Chromatids move towards opposite cell poles
What occurs during Telophase
- Chromosomes uncoil into chromatin
- Nucleoli reappear
- Disassembly of spindle
- Nuclear envelope reforms
What is the mechanism of action for 5-Fluorouracil as a chemotherapy?
Irreversibly inhibits thymidylate synthase, also a pyrimidine analog
What is the mechanism of action for Cyclophosphamide as a chemotherapy drug?
As an alkylating agent, it attaches alkyl groups onto guanines. This interferes with DNA replication and forms crosslinks
What is the mechanism of action for Epirubicin as a chemotherapy drug?
Induces intercalation of DNA strands, also triggers DNA cleavage by the topoisomerase II causing cell death
