Modern Genetics Flashcards
What is a genome?
All of an organism’s DNA
What are transcription factors?
Proteins which bind to DNA.
They bind to specific base sequences
What are promoter sequences?
Found upstream of the gene they act on
Enable the binding of RNA polymerase and therefore promote transcription
What are enhancer sequences?
Regulate DNA activity by changing chromatin structure (make it more or less open to RNA polymerase)
Open = active gene expression | Closed = gene inactivity - transcription factors either stimulate or prevent transcription of the gene
What is DNA methylation?
Addition of a methyl group to CpG on DNA
Prevents transcription and affects histone structure to make more/less DNA accessible to RNA polymerase
What is RNA splicing?
Post-transcriptional modification of mRNA
RNA splicing explains how eukaryotes produce more proteins than they have genes
Describe the process of RNA splicing.
Gene is transcribed which results in pre-mRNA
All introns and some exons are removed
Remaining genes are joined by spliceosomes
What can gene expression be changed by?
Epigenetic modification
; non-coding RNA, histone modification and DNA methylation
What is the importance of epigenetic modification?
To ensure cell differentiation
Define epigenetics.
Heritable and reversible modifications to the DNA that do not involve changes to the nucleotide sequence
Describe the first part of histone modification.
Acetylation - addition of an acetyl group which activates chromatin and allows transcription
Describe the second part of histone modification.
Methylation - addition of a methyl group, causes activation/inactivation of chromatin based on position of the lysine
How does RNA splicing result in different products from a single gene?
The same exons can be joined a variety of ways to produce several different versions of mature functional RNA.
What are stem cells?
Undifferentiated cells which have the ability to differentiate into many different cell types
What are the different types of stem cells?
Multipotent
Pluripotent
Totipotent