Storing and Using Genetic Information Flashcards
Phenotype
outward, physical manifestation of organism
Genotype
full hereditary information of an organism
What is a nucleotide composed of?
- sugar
- base
- phosphate group
What sugar is found in DNA?
2’-deoxyribose
Describe the curve of the double helix.
- Contains major and minor curves which provide stability
- Right-handed- spirals clockwise
What are the complementary base pairs?
- adenine and thymine (uracil in RNA)
- cytosine and guanine
Describe the structure of the nucleus
- largest organelle (usually)
- contains cells genetic material
- site of DNA replication and decoding
What are chromosomes?
a single piece of DNA containing many genes, regulatory element and other nucleotide sequences
What is chromatin?
the mixture of DNA, proteins and RNA that package DNA within the nucleus
What is the difference between heterochromatin and euchromatin?
- Heterochromatin= condensed and silenced
- euchromatin= extended and expressed
What do transcription and replication both require?
Two strands of DNA to separate temporarily to allow enzymes access to the DNA template
What possess barriers to enzymes?
nucleosomes and folding of chromatin
What are the 2 major mechanisms by which chromatin is made more accessible?
- histones can be enzymatically modified
- histones can be displaced by chromatin remodelling complexes
- both processes are reversible
Semi-conservative
one half of each new molecule of DNA is old, one half new
In what direction does DNA replication take place?
5’ to 3’
Where are Okazaki fragments formed
on the lagging strand
What does telomerase do?
replicates the 5’ end of the lagging strand
Exon
Coding region of DNA
Intron
non-coding region of DNA
Degeneracy
All of the amino acids (exc methionine and tryptophan) are encoded by more thatn 1 codon.
What is the mutation behind SCA?
single point mutation where hydrophilic glutamate is substituted to hydrophobic valine
What is mRNA?
- transcribed from DNA
- carries information for protein synthesis
What is the major role of RNA?
to participate in protein synthesis
Alternative Splicing
a process by which exons of the RNA produced by transcription are reconnected in multiple ways during RNA splicing
What determine the reading frame of RNA sequence
initiation codon
What is the major role of tRNA?
to translate mRNA into amino acid sequence and acts as an adapter molecule between the coded amino acid and the mRNA
Describe rRNA?
- component of ribosomes
- rRNA molecules are produced in the nucleus
- transported to cytoplasm, where they combine with proteins to form a ribosome
What is a polysome
when several ribosomes translate mRNA at one time
