Storing and Using Genetic Information Flashcards
phenotype
outward, physical manifestation of organism
genotype
full hereditary information of organism (even if not expressed) - genetic info that encodes phenotype
why are proteins all fucntionally different
due to their structure
what does protein structure depend on
specific sequence of amino acids
what is the molcecular structure of DNA (what does it contain)
Chain of nucleotide monomers with each nucleotide containing:
* Sugar (deoxyribose/ribose)
* Base
* Phosphate Group
structure of DNA
double helix with nucleotide base pairs connecting the two phosphate backbones. Leading and lagging strands 5’ to 3’ and vica versa. Contain minor and major groves
complementary base pairing
A-T
G-C
what does complementary base-pairing allow
to “unzip” DNA (read/expess) then put back together without breaking
what does the nucleus contain and what happens here
- most of the cell’s genetic material (DNA)
- replication of DNA and the first steps in decoding it for protein production
nucleolus
the largest nuclear organelle and is the primary site of ribosome subunit biogenesis in eukaryotic cells
what are chromosomes (what do they contain)
single piece of DNA containing many genes, regulatory elements and other nucleotide sequences
why do we fold dna into a highly ordered structure
takes up less space - allows for regulation
chromatin
what is it, sub-divided into
name given to the mixture of DNA, proteins and RNA that package DNA within the nucleus
Divided between heteochromatin (condensed) and euchromatic (extended) forms
what poses a barrier to enzymes trying to unzip dna
nucleosomes and folding of chromatin
2 main mechanisms by which chromatin is made more accessible
- histones can be enzymatically modified
- histones can be displaced bu chromatin remodeling complexes
processes are reversiable
dna replication: semi-conservative
one-half of eachh ne molecule of DNA is old; one-half new
how do proteins unzip the double helix
by breaking the hydrogen bonds
direction of DNA replication
bi-directional: only in 5’ to 3’ direction
what happens to dna before replication during cell division
chromosomes/dna lines up for cell division - can split in half cleanly
what happens to chromatin fibres to further fold dna
chromatin fibres repeatedly folded into a hierarch of multiple loops and coils
when are chromosomes most compacted (and visible)
during metaphase
exons
coding regions
introns
non-coding regions
set of 3 bases
codon
what does each codon specify
a particular amino acid - recognised by tRNA
how many different codons code for an amino acid
usually more than one (with exeption of couple AA)
what can single point mutations cause and give example
dysfunctional proteins: mutated haemoglobin gene causes Sickle Cell Anaemia - hydrophilic Glu is substituted by the hydrophobic Val (GAA/GAG –> GUA or GUG). hydrophobic Val causes clumping
what is the primary role of RNA
participate in protein synthesis
3 types of RNA
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
2 major steps of DNA replication
transcription then translation
role of mRNA
- transcribed from DNA
- carrier info for protien synthesis
alternative splicing
1 gene codes for multiple RNA transcripts which give multiple proteins
- allows is to have less genes
Reading frames
initiation codon of 3 nucleotides also deterimines the reading frame of the RNA sequence - if messed up inhibition codon (e.g. deletion mutation) then everything moves along 1 space (e.g. the fat cat –> hef atc at…) so completely different/non functional protein made
summarise process of DNA to functional protien and where this occurs
Nucleus:
DNA–transcribed–>mRNA–alternative splicing–>
Processed RNA leaves nucleus (to cytoplasm):
together with tRNA and rRNA makes protein–> post translational modifications
tRNA
- role to translate mRNA sequence into AA sequence
- acts as an adapter molecule between the coded AA and the mRNA
links codon and specific AA
rRNA
- component of ribosomes
- rRNA molecules produced in nucleus
- transported to cytoplasm where they combine with proteins to form a ribosome
what is a polysome
A polysome consist of a cluster of ribosomes that are held, simultaneously by a strand of messenger RNA (mRNA) in rosette or helical group. They contain a portion of the genetic code that each ribosome is translating and are used in formation of multiple copies of same polypeptide
process of dna replication
the opening of the double helix and separation of the DNA strands, the priming of the template strand, and the assembly of the new DNA segment - lagging strand done in segments
how is the base sequence of dna transcribed into rna
Transcription begins when RNA polymerase binds to a promoter sequence near the beginning of a gene (directly or through helper proteins).
RNA polymerase uses one of the DNA strands (the template strand) as a template to make a new, complementary RNA molecule.
Transcription ends in a process called termination. Termination depends on sequences in the RNA, which signal that the transcript is finished.
how is the base sequence of dna transcribed into rna
Transcription begins when RNA polymerase binds to a promoter sequence near the beginning of a gene (directly or through helper proteins).
RNA polymerase uses one of the DNA strands (the template strand) as a template to make a new, complementary RNA molecule.
Transcription ends in a process called termination. Termination depends on sequences in the RNA, which signal that the transcript is finished.
post-transcriptional processing of rna
splicing of exons (different orders allows for diff proteins to be expressed/diff folding (shape) and function)
translation of mRNA
mRNA travels to ribosomes where rRNA reads codons on sequence of nucleotide bases and instructs tRNA to “grab” AA accordingly. tRNA brings AA and they are joint together into primary protein structure
key enzyme used in dna replication
DNA poolymerase, adds complementary bases in 5’ to 3’ direction
role of DNA polymerase
responsible for the process of DNA replication, during which a double-stranded DNA molecule is copied into two identical DNA molecules
