Task 8 Revision Flashcards
What is the structure and organisation of DNA?
DNA is double stranded, it has a double helix shape. DNA has a phosphate sugar backbone and it consists of many nitrogenous bases (adenine, thymine, Guanine, and cytosine)
Organisation - normal DNA in GENOME, wraps around histones to form CHROMATIN, through cell division chromatin turns into chromatids, 2 copies of 23 types of chromatids make a chromosome.
What is the structure of RNA?
RNA is single stranded and shorter, it has a phosphate sugar backbone and consists of nitrogenous bases (adenine, uracil, guanine, cytosine).
What are the types of DNA and RNA? What is their function? and where are they located?
nDNA - is found in the nucleus
mtDNA - is found in the mitochondria
mRNA - is found in the nucleus, this transfers the genetic code to the ribosome
tRNA - is found in the cytoplasm, this carries the amino acids to the ribosome
rRNA - is found in the nucleolus, this creates ribosomes
What is the role of DNA?
DNA is the blueprint for all life, it contains the instructions needed for an organism to develop, survive and reproduce.
DNA determines the structure and function of cells.
What is the role of RNA?
RNA creates proteins through translation
What are the 3 types of genes?
- promoter gene
- regulator gene
- structural gene
what do the 3 genes code for?
promoter genes - indicate which structural gene should be transcribed during protein synthesis, it acts as a binding site for RNA polymerase which then attaches and copies the structural gene.
Structural gene - codes to produce proteins at ribosomes.
Regulator genes - prevents transcription, they produce repressor molecules that block RNA polymerase from binding to the promoter gene.
how do the 3 genes interact?
RG (on) –> PG (off) SG (off), no transcription
RG (off) –> PG (on) SG(on), yes transcription
RG (off) –> PG (off) SG (on), no transcription
RG (off) –> PG (on) SG (off), no transcription
what is the process of DNA replication?
happy, people, die, lonely
- Unwinding the DNA molecule - DNA helicase moves along the DNA strand and breaks hydrogen bonds, revealing nucleotides on the leading and lagging strand. primase then creates a sequence of nucleotides that attaches to the DNA strand and allows DNA polymerase to attach to the strand.
- Making new DNA strands - DNA polymerase then attaches to the primer and moves in a 5’ to 3’ direction joining free nucleotides. on the leading strand the formation is continuous, on the lagging strand Okazaki fragments of DNA are made, and then joined. DNA ligase moves along the strand, reforming hydrogen bonds.
- Rewinding the DNA molecule - each parent strand now has a complementary ‘new’ strand. DNA rewinds to form a double helix winds around histones and condenses to form chromatids. sister chromatids are joined together at the centromere and make a chromosome.
what is the product of DNA replication?
The result of DNA replication is two DNA molecules consisting of one new and one old chain of nucleotides
what enzymes are used in DNA replication?
happy, people, die, lonely
Helicase, Primase, DNA polymerase, Ligase
What is protein synthesis?
protein synthesis is the production of proteins in the cell
Processes occurring in Transcription
- Initiating Transcription “initiation” - transcription is initiated by a chemical messenger which enters the nucleus from the cytoplasm (hormone, drug). Chemical messenger binds to the DNA at the relevant gene and forms part of the epigenome, RNA polymerase binds to the promoter site.
- “Elongation” of mRNA strand - The RNA polymerase moves in a 5’ to 3’ direction unwinding the helix and breaking bonds. Forms a complementary mRNA strand using free nucleotides in the nucleus.
- “Termination” of RNA polymerase - RNA polymerase reaches a stop sequence in the DNA. mRNA strand is released, it contains introns + exons and undergoes splicing before leaving the nucleus to reach the ribosome.
DNA double helix is reformed.
Processes occurring in Translation
- Bind to ribosome - mRNA binds to a ribosome at codon ‘binding site.’ ribosomes move along the mRNA, one codon at a time. when it reaches the start codon (AUG) translation begins.
- Translation - tRNA in the cytoplasm have complementary anti-codon for mRNA codons.
anti-codon corresponds to a specific amino acid.
collect correct amino acids and deposit them at the ribosome. - PEPTIDE bonds - amino acids delivered at the ribosome, are joined by ‘peptide’ bonds.
1 ATP = 1 peptide bond
form polypeptide chain - Stop Codon - When the ribosome reaches a stop codon, translation is complete.
mRNA strand is released.
Polypeptide chain sent to GOLGI APPARATUS for packaging.
What is the difference between the epigenome and the genome?
The genome is the complete set of genetic material in an organism, while the epigenome is the set of chemical modifications to the DNA and DNA-associated proteins in the cell, which alter gene expression, and are heritable.
What occurs during acetylation?
Acetylation alters the arrangement of the histones - loosely bound genes are active, tightly bound genes are silenced
what is the process of acetylation?
- The DNA is negatively charged and the histones are positively charged, the laws of attraction mean that unlike charges attract, the DNA is coiled, therefore less, decreased transcription.
- Acetyl groups are negatively charged and attach to the histones making them more negative, the DNA and histones become more alike and begin to repel, uncoils. therefore there is more space and increased transcription.
what is transcription?
Transcription is the process of copying a segment of DNA into RNA.
what is translation?
Translation is the process that takes the information passed from DNA as messenger RNA and turns it into a series of amino acids bound together with peptide bonds.
what is methylation?
Methylation is the addition or removal of methyl groups (CH3) between guanine and cytosine.
What happens in methylation?
The addition of a methyl group silences a gene. it causes transcriptional repression by blocking the site for RNA polymerase attachment.
The removal of a methyl group using enzymes activates the gene for transcription.
what is gene regulation?
Gene regulation is the process of turning genes on and off.
How and when are epigenetic markers passed down?
Epigenetic markers turn genes on or off (acetylation, methylation), and imprinted tags are passed on from one generation to the next. most imprinted tags are lost during conception except for those that have been imprinted.
how do epigenetic tags effect the gene?
Epigenetic tags act as a gatekeeper to a genes ‘on’ switch. chemical tags are methyl groups or acetyl groups.
