what are histones
a special protein around which DNA is coiled to form chromatin
what is chromatin
a tangled network of DNA in the nucleus of a cell that is not dividing
What is DNA
Deoxyribose Nucleic Acid. Molecule in the nucleus of the cell that determines the type of protein a cell can make
What is a gene
Sections of DNA that contain genetic code for proteins
what are chromosomes
Rod like structures in the nucleus that carry hereditary info
Least complex to most complex
Gene, DNA, chromosomes
what is replication
replication is the process in which DNA makes an identical copy of itself prior to cell division.
what are the 5 steps of replication
- DNA is unzipped by Helicase
- Primase required to start replication.
- DNA polymerase binds to a single strand and builds a complementary strand (using free nucleotides in nucleus) 5’ to 3’ end
- ligase seals DNA fragments together
- DNA formed
what is protein synthesis
The process used by the body to make proteins by combining amino acids into protein chain. (small molecules into bigger)
what are the two processes of protein synthesis (in order)
Transcription (DNA –> RNA) and Translation (RNA –> proteins)
What are the 9 steps of transcription
- Takes place in nucleus
- Triggered by hormone that enters nucleus + binds to specific gene
- Helicase unzips DNA
- RNA polymerase attaches to begin process
- mRNA nucleotides floating around nucleus find their complement on DNA strand
- mRNA separates from DNA when copying is complete
- Introns remove junk DNA (RNA modification)
- mRNA enters cytoplasm + attaches onto ribosome
- DNA zips back up to form double helix
what are the nine steps of translation
- takes place at ribosome
- mRNA is read three codons at a time (starts with specific codon eg AUG)
- tRNA deliver Amino Acids to ribosome. Anticodon pairs up with complementary mRNA codon
- Ribosome works down mRNA strand. tRNA joins amino acids by formed peptide bonds
- polypeptide chain formed until a stop codon
- Multiple copies of protein is made. other ribosomes follow the first
- mRNA is recycled, broken up + nucleotides reused
- Proteins modified by folding, shortening in a unique way
- Protein transported to areas of the body that need them
what is an example of a start codon
AUG (methionine)
what are the three stop codons
UAA, UAG, UGA
how do genes control the synthesis of lipids and carbohydrates
no genes carry instructions to make them. however, the synthesis of these substances requires enzymes and enzymes are proteins. DNA carries instructions to make proteins
what is mitochondrial DNA
DNA found in the mitochondria
what are the two main differences between mtDNA and DNA
DNA is in the form of very long strands that are bound to proteins (histones). mtDNA is in the form of small circular molecules that are not bound to proteins
what is the pathway of DNA to proteins
DNA (stores info) –> transcription –> mRNA (carries info) –> translation –> protein (expression of info)
what are the two ways of chromatin remodelling
Histone modification (acetylation - enhances gene expression) Add methyl group to DNA (methylation - inhibits gene expression)
what is acetylation
addition of acetyl group to histones, causes DNA to unwind. Gene switched on
what is methylation
Addition of methyl group to DNA which causes DNA to coil tighter. gene switched off
what are the 7 environment factors that can effect a persons epigenome
Severe stress, nutritional factors, toxins, drugs, smoking, aging, lifestyle
what is epigenetic
Altering expression of a gene without changing the gene structure
