IMS topic 1
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- Created by: Ettie Conway
- Created on: 02-04-24 18:05
the genome
all the genetic information of an organism
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how many nucleotides in humans?
3.2 billion
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genome makeup
2 sex chromosomes, 44 autosomes, 37 genes on mitochondrial chromosomes
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karyotype
image of chromosomes arranged by size and type
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percentage of coding DNA
1%
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tandem repeats
repeated short DNA sequence occured due to polymerase slippage
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senescence
when telomeres can't shorten anymore
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pseudogenes
A DNA sequence that resembles agene but has beenmutated into an inactive form over the course of evolution
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n= 23
haploid cells
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n=46
diploid cells
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n> 46
polyploid cellss
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bar body
inactivated x chromosome in a woman pushed to edge of the nucleus
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which is not a reason why RBCs lose their nucleus?
allows RBCs to go undetected by WBCs
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pufferfish % coding DNA
10%
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have 2n chromosomes per cardiomyocyte throughout life, and can repair heart damage as adult
zebra fish
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have 2n chromosomes per cardiomyocyte and canrepair heart damage while newborns
newborn mice
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synteny
when long DNA sequences are present in the same order in different species (translocation throughout evolution)
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A single nucleotide polymorphism (SNP)
a variation at a single position in a DNA sequence among individuals
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what % of population has to show change for it to be classed as a SNP?
1%
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If a SNP occurs within a gene, then the gene is described as having
more than 1 allele
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aneuploidy
wrong number of chromosomes
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non dysjunction
failure of chromosomes to properly separate
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downs syndrome
trisomy 21
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chronic myeloid leukaemia
philadelphia chromosome 9;22
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cystic fibrosis CFTR gene mutation
single mutation
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huntington's disease mutation
increased CAG tandem repeats in the Huntingtin protein
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why is all mitochondria from mother?
capacitation of sperm
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nucleotide formed of
phosphate, pentose sugar and base
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purines
adenine and guanine
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pyramidines
thiamine and cytosine
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covalent phosphodiester bonds DNA
between 5' and 3'
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2 hydrogen bonds between
adenine and thiamine
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3 hydrogen bonds between
guanine and cytosine
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coding dna
DNA transcribed into mRNA
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structural RNA
ribosomal rRNA and transfer tRNA
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regulatory RNA
microRNA, Xist
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xist
switches off one copy of the X chromosome in ** cells creating a Barr body
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nucleosomes
dna wrapped tightly around histones
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chromatin fibres
coiled nucleosomes
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chromosomes
chromatin fibres on a protein scaffold
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not a step of double helix unzipping
dna polymerase guides dna helicase
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function of primase
attaches an RNA primer which acts as astart point to attach nucleotides
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DNA polymerase iii
adds nucleotides from 5' to 3' and deletes nucleotides from 5' to 3'
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not a part of sticking okazaki fragments together
use Pol III has 5 to 3 polymerase and 5 to 3exonuclease activity
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silent mutation
doesn’t change amino acid sequence
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missense mutation
changes to a different amino acid
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nonsense mutation
changes codon to a stop codon
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frameshift mutation
shifts reading frame (so rest of protein also affected)
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transcription
The synthesis of messenger RNA (mRNA) using DNA as a template
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translation
the process which a sequence of nucleotide triplets in a messenger RNA gives rise to a specific of amino acids during the synthesis of a polypeptide chain or protein
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splicing
Removal of intronic sequences from the pre-mRNA. The exonic sequences are spliced together. The number of exons varies greatly between genes.
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How is transcription started?
TFIID transcription factor recognises TATA box/ promoter region
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not a step of transcription initiation
TFIIB, recognises the TATA box and ensures that the correct start site is used
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alteration of promoter strength effect
can have deleterious effects upon a cell, often resulting in disease
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transcription elongation
The DNA double helix unwinds and RNA polymerase reads the template strand, adding nucleotides to the 3′ end of the growing chain
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where are terminator sequences found?
close to end of non-coding sequences
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pol 1 genes termination
transcription is stopped using a termination factor, through a mechanism similar to rho-dependent termination in bacteria
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pol ii genes termination
transcription ends after transcribing a termination sequence that includes a polyuracil stretch
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pol iii genes termination
Transcription can continue for hundreds or even thousands of nucleotides beyond the end of a noncoding sequence
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post transcriptional modifications - ribosomal RNA
After synthesis (45S), it splits into small fragments 28S,18S and 5.8S by RNases
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post transcriptional modifications - 5' capping in eukaryotic cell
7-methylguanosine attached backwards through a triphosphate to the 5’ terminal end of the RNA. To stabilise RNA and translate protein
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post transcriptional modifications - addition of a poly-a tail in the eukaryotic cell
40-200 adenine nucleotides attached to the 3’ end of the RNA. To stabilise mRNA and to transfer through nuclear membrane
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post transcriptional modifications - splicing in eukaryotic cell
Removal of introns
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how is tRNA an "adaptor molecule"
One end can read the triplet code in the mRNA through complementary base-pairing, and another end attaches to a specific amino acid
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rRNA function
catalyzes the attachment of each new amino acid to the growing chain
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not a step of translation initiation
formation of a complex on the tRNA
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translation elongation translocation
The ribosome moves along the mRNA in the 5'-to-3’ direction, which requires the elongation factor G,
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not a step of translation elongation
Transcription ends after transcribing a termination sequence that includes a polyuracil stretch.
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stop codons
UAA UAG UGA
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stop codons are recognised by
release factors, which fit into the P site
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splicing reactions
2 transesterification reactions
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first reaction of splicing
transesterification of free 2'hydroxy group
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2nd splicing reaction
the 3'-hydroxy group of the 5' exon attacks and cleaves the phosphodiester linkage at the 3' splice site. T
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self- splicing
The intron folds into a specific conformation without the involvement of other RNA or protein
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alternative splicing
the process by which a given gene is spliced into more than one type of mRNA molecule.
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not a role of splicing
regulation of cell replication and apoptosis
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methionine start codon
AUG
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name of theory:
specificity for the base at the 3’ end of the codon is not always observed explaining why multiple codons can code for a single amino acid
specificity for the base at the 3’ end of the codon is not always observed explaining why multiple codons can code for a single amino acid
wobble hypothesis
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protein trafficking
the mechanism by which a cell transports proteins to the appropriate locations either inside or outside the cell
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cytosolic pathway
no signal peptide: cytosol to plasma membrane, mitochondria and nucleus
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secretory pathway
signal peptide: ER to golgi to secretory vesicles, lysosomes and plasma membrane
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signal peptide
directs the protein from the cytoplasm into a specialisedcellular compartment
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what happens to proteins that lack a signal peptide - cytosolic pathway
are not translocated into the Golgi and are not processed. synthesized on free ribosomes not associated with the rough endoplasmic reticulum
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cytosol modifications
Acetylation, Prenylation, Myristoylation, Palmitoylation
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Post-translational attachment of lipids to proteins creates
non-membrane spanning integral membrane proteins that will reside on the cytoplasmic surface of the plasma membrane of subcellular membranous organelle
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myristolylation
use of protease. the high energy thioester is used to drive the synthesis of the low energy amide linkage
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bonds and enzymes used to form insulin
disulfide bonds, prohormone convertase and carboxypeptidase H
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o- linked glycosylation
The attachment of sugars to serine or threonine (simple)
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n-linked glycosylation
The attachment of sugars to asparagine (difficult)
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cancer development
cell with genetic mutation, hyperplasia, dysplasia, in situ cancer, invasive cancer
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not a hallmark of cancer
increased permeability of cells leading to swelling and escaping of protein-rich exudate
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carcinogenesis
Multistep process that acquires and accumulates mutations which enable the cells to acquire the “hallmarks”
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Other cards in this set
Card 2
Front
how many nucleotides in humans?
Back
3.2 billion
Card 3
Front
genome makeup
Back
Card 4
Front
karyotype
Back
Card 5
Front
percentage of coding DNA
Back
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