Question

Cell Biology: Gene Structure & Organization

Answer 1

Note: This is a reference for educational/studying purposes, not a question, please save all comments or questions for the end.

Answer 2

\({\bf{Introductory~Vocabulary}}\)

- enhancers: transcriptional control regions
- polycistronic: mRNAs that can encode for multiple proteins (characteristic of bacteria)
- monocistronic: mRNAs that can only encode for one protein (characteristic of eukaryotes)
- simple transcript: yields one type of mRNA (characteristic of bacteria)
- complex transcript: yields multiple mRNA (most eukaryotic transcripts are complex) due to processing/ alternative splicing
- solitary genes: genes only occuring once in the haploid genome
- gene family: set of repeated genes encoding similar amino acid sequences and closely related proteins
- pseudogenes: genes with different sequences than the normal equivalents due to sequence drift (accumulation of mutations over time)
- tandemly repeated arrays: duplicated genes that encode identical or near identical proteins/RNAs, arose to help increase production of proteins that are needed in high quantities by the cell
- genetic complementation: test to determine if two mutations come from the same/different genes

\({\bf{Functional~RNAs}}\)
- snRNAs: involved in RNA splicing
- snoRNAs: involved in pre-rRNA processing + base modification
- miRNAs: stability and translation of mRNAs, gene expression

Answer 3

\({\bf{Why~Noncoding~DNA~exists}}\) : selective pressures on eukaryotes are different, genes are expressed at lower levels, so the energy expenditure associated with having long stretches of noncoding DNA is not enough to remove it

\({\bf{satellite~DNA}}\) short repetitious DNA sequences, may be involved in mitosis and chromosome end preservation
- subtypes, minisatellites (14-100bp) and microsatellites (1-13 bp)
\({\bf{interspersed~repeats}}\) longer repetitious DNA sequences

differences in repeat length come from unequal crossing over during meiosis
DNA polymorphism: differences in sequences between individuals within a species

Answer 4

going to get back to this when I'm not so tired, will be covering mobile elements