Lecture 2 - Gene expression regulation: introduction Flashcards
Genome
the complete set of sequences in the genetic material of an organism
The genome includes the
sequence of each chromosome plus any DNA in organelles
Transcriptome
the complete set of RNAs present in a cell, tissue, or organism
Proteome
the complete set of polypeptides produced by a cell
Chargaff’s rule
The amount of adenine approximately equals the amount of thymine (and cytosine ~ equals guanine)
The phosphate group in DNA is linked to
a deoxyribose sugar
Open chromatin is called
euchromatin
Closed chromatin is called
heterochromatin
Heterochromatin is
densely packed
Euchromatin is
loosely packed
in heterochromatin, transcription
cannot occur
In euchromatin, transcription
can occur
Size from smallest to largest of chromatin fiber, nucleosome, chromosome, DNA
DNA, nucleosome, chromatin fiber, chromosome
Chromosome
a discrete unit of the genome carrying many genes
Each chromosome consists of
a very long molecule of duplex DNA
Each chromosome is approximately equal masses of
DNA and protein
Chromosomes are visible as a morphological entity only during
cell division
How many human chromosomes are there?
46
How many chromosomes in yeast, nematode, and fruit fly?
32, 12, 8
Central dogma
information can only be transferred between nucleic acids and from nucleic acid to protein
Viroid
a small infectious single-stranded circular RNA molecule that does not have a protein coat
Prion
A proteinaceous infectious agent that behaves as an inheritable trait even though it contains no nucleic acid
Genes are the basic units of
inheritance
Genes are ________ of the genome
functional units
The human genome contains about _______ genes
20,000
A chromosome is a very long molecule of
DNA
A gene will give rise to
a polypeptide or an RNA
Allele
One of several alternative forms of a gene occupying a given locus on a chromosome
Locus
The position on a chromosome at which the gene for a particular trait resides
Genetic recombination
A process by which separate DNA molecules are joined into a single molecule
All mutations are changes in
the sequence of DNA
Mutations may occur spontaneously by
DNA replication errors
Mutations may be induced by
mutagens
Mutation examples
Point mutations
Missense mutations
Silent mutations
Nonsense mutations
Frameshift mutation
Every coding sequence has ______ possible reading frames
3
Open reading frame
A sequence of DNA consisting of triplets that can be translated into amino acids starting with an initiation codon and ending with a termination codon
An open reading frame starts with sequence
AUG
3 stop codons
UUA, UGA, UAG
The genetic code is read in triplet nucleotides called
codons
Gene expression
The process by which the information in a sequence of DNA in a gene is used to produce an RNA or polypeptide, involving transcription and translation
RNA has the same sequence as the
DNA top strand (with U instead of T)
Each mRNA consists of
a 5’ UTR, a coding region, and a 3’ UTR
Introns are part of the gene that are
not represented in the polypeptide product
Introns are removed from the pre-mRNA transcript by
splicing
RNA processing
Modifications to RNA transcripts of genes
pre-mRNA
The nuclear transcript that is processed by modification and splicing to give an mRNA
Exon
Any segment of an interrupted gene that is represented in the mature RNA product
Pol I is in
rRNA
Pol III is in
tRNA
Pol II is in
mRNA
Ribosome
A large assembly of RNA and proteins that synthesizes polypeptides under direction from an mRNA template
rRNA
A major component of the ribosome
tRNA
The intermediate in polypeptide synthesis that interprets the genetic code
Promoters and enhancers are ______ acting DNA elements
cis
An upstream-activating sequence (UAS)
behaves like an enhancer, but only works upstream of the promoter
All gene products are ______ acting
trans
Trans-acting elements
Transcription factors (TFs), RNA-binding proteins (RBPs), miRNAs
