Week 1 Flashcards
What is Heredity?
Process in which traits pass from one generation to the next one without being altered.
Why is heredity important?
DNA keeps the fidelity of those traits.
What happens when DNA doesn’t keep the fidelity of various traits?
when this is not happening changes in DNA cause modifications.
What are the biological functions of proteins?
Responsible for most biological functions like Structure, movement etc.
What is the purpose of DNA?
Stores heritable information.
Set of instructions to build and maintain an organism is stored in the DNA.
Provides continuity between generations.
Is the substrate for evolution (Natural selection is going to try and preserve those alleles.
Where is DNA found in eukaryotic cells?
Nucleus
Mitochondria
Chloroplasts
Where is DNA found in prokaryotic cells?
Circular chromosome in the nucleoid
Plasmids
What are the building blocks of DNA?
Nucleotides
Nitrogenous base
Pentose sugar
Phosphate group
What is created Without the phosporus group?
nucleosides
What are the four bases?
guanine, adenine, Cytosine, thymine, (uracil)
What are the 4 nucleosides?
guanosine, Adenosine, Cytidine, thymidine, (uridine)
What are the 4 nucleotides?
guanylate, Adenylate, Cytidylate, thymidylate, (uridylate)
How are nucleotides linked?
by phosphodiester bonds
Pyrimidines contain what?
Cytosine
Thymine (T in DNA)
Uracil (U in RNA)
What do Purines contain?
Adenine
Guanine
What does the DNA strand contain?
All have a sugar-phosphate backbone.
Has directionality 5’ to 3’
How was the structure of the double helix discovered?
Structure of DNA was solved by Watson and Crick using X-ray data collected by Rosalind Franklin
What are the features of the double helix?
Relatively hydrophobic nitrogenous bases in the molecule’s interior
Negatively charged phosphate groups in the exterior
Sugar-phosphate backbone
Weak hydrogen bonds hold the two strands together
What are the base pairings?
“Chargaff’s ratios”: Ratio of A : T and G : C bases always the same
This is because A always pairs with T, and C with G
What are bacterial chromosomes?
Usually a single circular DNA molecule
DNA packed with a small amount of proteins
What are Eukaryotic chromosomes?
The genome is found in multiple chromosomes
Each chromosome contains is a linear DNA double helix
DNA packed with a large amount of proteins (this is called chromatin)
Why is packing necessary?
DNA is very long.
Long DNA molecules in chromosomes need to be packed so they fit into the cell.
Average length of DNA in human chromosomes: 1.5 x 108 base pairs
Length of 1 DNA molecule = ~ about 4 cm
There are 46 DNA molecules in a human cell
4cm * 46 = Total length of DNA 184 cm
How is DNA packed?
Packed by histone proteins. Histones leave DNA briefly, during DNA replication and transcription
Chromosomes are NOT _______ organised in the nucleus.
Randomly.
What is active chromatin?
Euchromatin: loose chromatin structure, active for transcription (DNA transcribed to RNA).
What is inactive chromatin?
Heterochromatin: condensed chromatin structure, inactive for transcription.
What is a gene?
Sequence of nucleotides that encodes the synthesis of a gene product, either RNA or protein
The order of the nucleotides determines the order of monomers in a polypeptide or nucleic acid molecule
What does the promoter on the gene do?
(controls expression of
the gene) can be switched on or off.
What do genes have at the 5’ end?
Genes have a start codon
= ATG nucleotide sequence
What do genes have at the 3’ end?
Genes have a stop codon
(several different sequences
What is a genome?
The complete set of genetic material present in a cell or organism
What is genomics?
Study of the whole genomes.
What does genomics contain?
Sequencing of genomes
Study of evolution of genomes
Study of regulation of whole genomes
Behavioural genomics
What is transcriptomics?
Study of all the mRNAs present in an organism or cell.
What is Proteomics?
Study of all the proteins present in an organism or cell.
What is Metabolomics?
Study of all the metabolites in an organism or cell.
What is Epigenomics?
Study of all the epigenetic state of the whole genome.
What is a genetic locus?
A particular location on the genome or on a chromosome.
Most often refers to a gene
But it can also refer to just one nucleotide in the genome (e.g. that has a mutation)
It can be used to refer to a whole gene
It can be used to refer to other bits of DNA that are not genes
What is semi-conservative replication?
Each strand serves as the template for replication of a new strand of DNA
What is the origin of replication?
DNA replication starts at a specific location in the genome
How many origins are in bacterial chromosomes?
Only 1
How many origins are in eukaryotic chromosomes?
May have hundreds or even thousands of origins
What is the very active area where DNA replication takes place known as?
Replication fork or bubble
How do replication forks move?
In opposite directions.
What is required for DNA replication?
Multiple enzymes
What occurs due to Topoisomerase?
unwinds DNA, helix to ladder
What occurs due to Helicases?
unzips DNA, double-stranded DNA (dsDNA) to single-stranded DNA (ssDNA)
What do Single-stranded binding proteins do?
stabilizes ssDNA
What do primase do?
RNA polymerase, sets RNA primer to start new strand.
What does DNA polymerases do?
adds new nucleotide based on complementarity with DNA template.
What do DNA ligase do?
links the nucleotides in the new strand
What can DNA polymerases not do?
Cannot start a DNA chain, only extend it.