Molecular Genetics Lectures Flashcards
Irreversbility
you can’t recreate progenitor generation
you can’t recreate progenitor generation
Irreversbility
Eukaryotes
animals – plants – fungi
animals – plants – fungi
Eukaryotes
DNA
Deoxyribo – Nucleic – Acid
RNA
Ribo – Nucleic – Acid
The backbone
triphosphate and a base (a sugar)
is made out of a triphosphate and a base
The backbone
Base pairs are bound by
by phosphoiester bonds
bound by phosphoiester bonds
Base pairs
polynucleotide
a long chain of nucleotides
= DNA
DNA chemically
polynucleotide
a long chain of nucleotides
Connections between the base pairs
are very weak
Connections between them are very weak
base pairs
First function of DNA
DNA replication = copying
Second function of DNA
Gene expression
5-3 strand
coding strand
sense strand
coding strand
5-3 strand
sense strand
sense strand
coding strand
5-3 strand
3-5 strand
template strand
anti-sense strand
starts transcription
RNA polymerase
End of transcription is signaled by
upstream signal AAUAAA
upstream signal AAUAAA
End of transcription is signaled by
Exon
Codes
Coding part
exon
Intron
Does not code
Non-coding part
Intron
Non-coding RNA
rRNA = ribosomal RNA tRNA = transfer RNA
rRNA = ribosomal RNA tRNA = transfer RNA
Non-coding RNA
tRNA
= transfer RNA
Transfers amino acids to the protein chain
Transfers amino acids to the protein chain
tRNA
possible codons n
64
amino acids n
20
stop codons n
three
initiation codon n
one
tRNA
= tRNA
Transcribes the mRNA into the polypeptide
tRNA has a cloverleaf structure
Transcribes the mRNA into the polypeptide
tRNA
has a cloverleaf structure
Four arms of tRNA
Acceptor arm, connects to the codon
D arm and TpsyC arm
Anticodon arm
Base wobble
Reduces the number of ribosomal RNAs needed
by enabling on transfer RNA to read different codons
Reduces the number of rRNAs needed
by enabling on tRNA to read different codons
Base wobble
Eukaryotic cells
almost always belong to a multicellular
almost always belong to a multicellular
Eukaryotic cells
Prokaryotes
don’t have a membrane that surrounds the nucleus
don’t have a membrane that surrounds the nucleus
Prokaryotes
yeasts, protophyta, protozoa
unicellular versions of fungi, plants and animals
unicellular versions of fungi, plants and animals
yeasts, protophyta, protozoa
Prokaryotes
made up of bacteria of archaea
made up of bacteria of archaea
Prokaryotes
Endosymbiosis
one cell within another
one cell within another
Endosymbiosis
Most somatic cells are diploid, except:
Some cells are nulliploid, have lost their DNA nucleus
Some cells are polyploid
Example: many blood cells
nulliploid
Examples are liver cells and cardiomyocytes
polyploid
Cell life phases
G1, S, G2 and M
M phase
seperation
seperation
M phase
Early S phase
Late S phase
One chromosome arm
Two chromosome arms
One chromosome arm
Two chromosome arms
Early S phase
Late S phase
Phases of mitosis
Interphase Prophase Prometaphase Anaphase Telophase Cytokinesis
methods to create variation
Recombination
independent assortment
Two methods of amplifying DNA
Cell-based DNA cloning
Polymerase chain reaction
Bacterial cloning method
Living culture of bacteria
Transformation
Amplification
Isolation of recombinant DNA
Cut open phosphodiester bonds
Restriction endonuclease
Restriction endonuclease
Cut open phosphodiester bonds
Host cells in cloning
yeast
bacteria -> plasmids
bacteriophage
PCR ingredients
DNA
Polymerase
Two primers
All four nucleotides
Steps of amplification
- Denaturing
2. Nucleotides attach to the single strand
Advantages PCR
Straightforward and quick
Only tiny amount of DNA is needed
Problems with PCR
The sequence of boundary regions must be known
Genomic library
Cloned DNA fragments
Representing the entire genetic material of an organism
Sanger sequencing:
Ingredients
The fragments
Primer
Polymerase
dNTP and ddNTP (needed to form a connection with the next nucleotide)
Issues with Sanger sequencing
Error prone
cluttered
More advanced method
Everything on one plate
Iterative pyrosequencing
Based on emitted light
In Sanger sequencing
Massively parallel sequencing of amplified DNA
-> Next generation
This method can only sequence small fragments
Assembly
Based on overlapping fragments
Done by computer
Based on overlapping fragments
Done by computer
Assembly
Hybridization
Catch the target or test DNA / RNA fragment
by a complementary probe
Catch the target or test DNA / RNA fragment by a complementary probe
Hybridization
International HapMap project
Project to summarize all SNPs
Project to summarize all SNPs
International HapMap project
Centimorgan
Measurement unit
One map unit is equivalent to a 1% recombination frequency
Physical maps
Based on actual distances between loci and nucleotides
Based on actual distances between loci and nucleotides
Physical maps
HP LC-MS
= high performance mass spectronomy Molecule is destroyed Are accelerated Hit a detector Time and intensity is measured Determines what molecule it is
Chromatin
the whole complex of DNA and the associated proteins
the whole complex of DNA and the associated proteins
Chromatin
Euchromatin
unpacked / less packed
unpacked / less packed
Euchromatin
Centromere
essential for segregation during cell division
essential for segregation during cell division
Centromere
Telomere
Long area of tandem repeats
End part of chromosome
Long area of tandem repeats
End part of chromosome
Telomere
Mitochondria DNA
Have circular DNA
Similar size to bacteria
No introns
50% codes
Mitochondrial replacement therapy
To treat women with mitochondrial diseases that want to get pregnant
Because the mitochondria are transmitted in 100% of cases
Why do we still don’t have an exact number of human genes
Depends on the definition
e. g. three different genes or versions of one?
Sequence homology searches
searches for homologous gene sequences
searches for homologous gene sequences
Sequence homology searches
Chimera
mouse whose cells are a mixture of mutant and wild type
mouse whose cells are a mixture of mutant and wild type
Chimera
Characteristics of Proteomics
Time dependent
Environment dependent
Post-translational modifications
Metabolomics
Studies energy and lipid household of the body
Studies energy and lipid household of the body
Metabolomics
Types of variation between human genomes
SNPs
Tandem repeats
Mutations
Recombination
Mutation types
Base substitution = point mutation
Deletions and insertions
Frequency of mutations
Error occurs in one of every 50 million nucleotides
Correction mechanisms fix mistakes in DNA polymerase
External sources of mutations
Radioactivity
(Sun) light
Anti-cancer drugs
- Aimed at damaging DNA in cancerous cells
endogenous causes of mutation
Segregation
Recombination
Replication
Segregation
Recombination
Replication
endogenous causes of mutation
other causes of mutation
Spontaneous chemical events
Radiation
External chemicals
Spontaneous chemical events
Radiation
External chemicals
other causes of mutation
Five damage types
Strand breakage Double strand breakage Base deletion Chemical modifications of bases Base or string cross-linking
Repairing DNA
Base-excision repair (BER)
Nucleotide-excision repair (NER)
Recombination-mediated
Undetected Damage
Deamination: loss of an amino group
Deamination
Undetected Damage
loss of an amino group
SNPs
Single nucleotide polymorphisms
1 in every 300
Most have two alleles, some have three
Interspersed or tandem repeats
Micro or mini
Comprise 50% of human genome
Mini or micro satellites
Interspersed or tandem repeats
Comprise 50% of human genome
Germ-line mutation
Mutation Between generations
Mutation Between generations
Germ-line mutation
High-speed, on demand variation
In reaction to disease, pathogens, anything invasive
= adaptive immune system
adaptive immune system
High-speed, on demand variation
In reaction to disease, pathogens, anything invasive
= adaptive immune system
Categories of genes
Coding genes, RNA genes, pseudo genes and repeats
Only 1-4% coding
45% RNA genes
45% repeats
Gene silencing
only reading the DNA that is necessary
Achieved by microRNA
Gene duplication mechanisms
Unequal crossover
Gene duplication by ancestral fusion of cells
Unequal crossover
Gene duplication by ancestral fusion of cells
Gene duplication mechanisms
Effect of gene duplication
families of genes
Have similar biochemical functions
families of genes
Have similar biochemical functions
Effect of gene duplication
Constitutive heterochromatine
Around centromere
Mostly long arrays of high-copy number tandem repeats
-> selected by evolution to be shut down
Around centromere
Mostly long arrays of high-copy number tandem repeats
-> selected by evolution to be shut down
Constitutive heterochromatine
Transposon
mobile DNA sequences that can migrate to different genome regions
45% of genome
“Virus-like DNA”
Mobile DNA sequences
Can migrate to different genome regions
45% of genome
“Virus-like DNA”
Transposon
Retrotransposon repeat
Work with copy and paste
Work with copy and paste
Retrotransposon repeat
DNA transposon
Cut and paste
Work with Cut and paste
DNA transposon
“Fossil” transposon
Not active anymore
DNA replication
DNA polymerase producing two identical replicas of DNA from one original DNA molecule
Different stages of the cell cycle
M (Mitosis/Meiosis)
Interphase (G1, Early S = DNA replication, Late S, G2)
Stages of mitosis
Prophase Prometaphase Metaphase Anaphase Telophase
minisatellite
Repetitive DNA
Certain DNA motifs
(ranging in length from 10–60 base pairs)
Repeated 5-50 times.
Repetitive DNA
Certain DNA motifs
(ranging in length from 10–60 base pairs)
Repeated 5-50 times.
minisatellite
Repetitive DNA
Certain DNA motifs
(ranging in length from 1 to 6 or more base pairs)
Repeated, typically 5–50 times.
microsatellite
microsatellite
Repetitive DNA
Certain DNA motifs
(ranging in length from 1 to 6 or more base pairs)
Repeated, typically 5–50 times.
coactivator
Transcriptional coregulator
Binds to a transcription factor
Increases the rate of transcription
Type of transcriptional coregulator
Binds to a transcription factor
Increases the rate of transcription
coactivator
oligonucleotide
a polynucleotide whose molecules contain a relatively small number of nucleotides.
a polynucleotide whose molecules contain a relatively small number of nucleotides.
oligonucleotide
a process of cell duplication, in which one cell divides into two genetically identical daughter cells.
mitosis
mitosis
a process of cell duplication, in which one cell divides into two genetically identical daughter cells.
a division of a germ cell involving two fissions of the nucleus and giving rise to four gametes
meiosis
meiosis
a division of a germ cell involving two fissions of the nucleus and giving rise to four gametes
a covalentbondlinking two amino acids
peptide bond
peptide bond
a covalentbondlinking two amino acids