DNA & RNA Flashcards
Nucleotide
Consists of a sugar molecule attached to a phosphate group and a nitrogen base
Gene expression
The process where information in a gene is used to make a product (protein)
Transcription
The process by which mRNA is formed, using the code on a DNA strand (antisense) by matching the sequence of nucleotides
Nitrogenous bases
Thymine Guanine Adenine Uracil Cystosine
Messenger RNA
The RNA molecule that transfers coded information from the nucleus to ribosomes
Intron
Non-coding sections of RNA transcript
Exxon
Part of the RNA transcript that includes a section of the final piece of RNA after introns have been removed during RNA splicing
Helicase
The enzyme responsible for the separation of DNA strands during replication
Base triplet
A group of 3 nitrogenous bases on the DNA strand
Template strand
The strand of DNA corresponding to the mRNA sequence
Coding strand
Identical to the strand of mRNA being produced, but containing thymine instead of uracil
Translation
The process occurring inside the ribosome, turning tRNA into amino acids, which then turn into protein
Start codon
The first codon of mRNA translated by risbosomes - AUG
Methionine
A hydrophobic amino acid
Anticodon
A trinucleotide sequence, complimentary to that of a corresponding codon in mRNA
Promoter sequence
Initiates the transcription of the first codon from a DNA triplet
Terminator sequence
Signals termination of transcription to RNA polymerase
RNA polymerase
The enzyme that transcripts DNA sequences into RNA
What are the 3 stages of translation
Initiation
Elongation
Termination
Initiation
mRNA enters the ribosome and tRNA anticodon binds to start codon (aug)
Elongation
More tRNA binds to the mRNA and attached amino acids bond together (peptide bond), forming a polypeptide chain. Initial tRNA breaks off.
Termination
When polypeptide is complete, a stop codon is recognised and a primary protein is formed.
Stop codon ( UAA, UAG, UGA)
Epigenome
a multitude of chemical compounds that tell the genome what to do. The epigenome is made up of chemical compounds and proteins that can attach to DNA and turn genes on and off
Methyl
- Silence/turn off transcription
- Attach to cytosine at CG
Acetyl
Loosens interaction between DNA and histones, creating a larger surface are for translator enzymes to decode. Attach to amino acid lysine tail on histones
Can there be multiple codons for an amino acid?
Yes
What are the stages of mitosis
Ipmat- Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
What are the characteristics of an active gene?
Wrapped loosely around his tone
Few methyl molecules attached
Many acetyl molecules
Many mRNA transcripts
What are the characteristics of an inactive gene?
Gene wrapped tightly around histone
Many methyl molecules attached
Few acetyl molecules
Few mRNA transcripts
What are the 3 ways variation can occur in a gene?
Via crossing over (division 1)
Random alignment
Independent assortment
What cells does mitosis occur in?
eukaryotic cells - a cell with a nucleus
What’s the sequence of events of DNA replication
- helicase splits DNA strands
- Primase lays a primer segment on leading strand
- DNA polymerase binds to primer and lays complimentary nucleotide bases to the original strand
- primase primes fragments on lagging strand
- polymerase adds bases in Okazaki fragments, working 5” - 3”
- Exonuclease removes all primers from both stands
- DNA polymerase fills in gaps
- DNA ligase seals fragments, forming continuous strand
What’s helicase used for
Splits the DNA strands
What’s DNA polymerase used for?
Adds bases to DNA strands
What removes the primers from the DNA strand during DNA replication
Exonuclease
What’s a totipotent stem cell
Forms the embryo and it can give rise to any cell necessary for embryonic development.
Which stem cell is capable of becoming most but not all tissue cells in the human body?
Pluripotent
What’s a multipotent cell?
A cell with potential to form a number of different cells, specialised to their type.
Eg. Stem cells in bone marrow make blood cells only - not muscle tissue/ bone tissue/ nervous tissue
Link stem cells to mitosis and gene expression
As cells undergo mitosis, different genes become activated due to its environment, in turn making cells specialised to a particular task.
Stem cells can either undergo mitosis ( stochastic differentiation) or form specialised cells (both forms of differentiation)
Define differentiation in stem cells
When a cells environment impacts the activation and deactivation of certain genes, making the daughter cells specialised to a particular task
Definition of stem cell
- unspecialised cells
- potential to give rise to diff. types of cells within the body
- used for growth and repair
What are the two ways a stem cell can differentiate
- obligate asymmetric replication ( daughter cell)
- stochastic Differentiation (mitosis)
What are examples of post transcriptional modification
Poly-A-tail, guanine cap, RNA splicing
What are the 3 types of stem cells
Totipotent, pluripotent, multi potent
