Chapter 21 Flashcards
Pseudogenes
Former genes that have accumulated MUTATIONS and are nonfunctional
they are not expressed
Repetitive DNA
present in multiple copies of the genome
Transposable elements
Move from one site to another in a cell’s DNA
Transposons and retrotransposons
Present in Eukaryotes and prokaryotes
Transposon
Move by means of a DNA intermediate
Require a transposase enzyme
Retrotransposons
Move by means of RNA intermediate
Use reverse transcriptase
Alu elements
Large portion of transposable elements
found in primates
Represent the result of transposition
What do many Alu elements code for?
RNA
can help regulate gene expression
Simple sequence DNA
contains many copies of tandemly repeated short sequences
Short Tandem Repeat (STR)
series of repeating 2-5 nucleotides
Multigene families
Collections of identical or very similar genes
Often code for rRNA
a-globins and b-globins
Non-identical multigene families
can be coded at different times for hemoglobin
Polyploidy
Extra sets of chromosomes
Lysozyme
Duplicated and evolved into the gene that encodes a-lactalbumin in mammals
Helps with milk production
Exon shuffling
contributed to genome evolution
rearranges exons
What happens if you insert transposable elements within a protein-coding sequence?
Could block protein production
What happens if you insert transposable elements within a regulatory sequence?
Increase or decrease protein production
Highly conserved genes
Change little over time
Evo-devo
The study of the evolution of developmental processes in multicellular organisms
Homeobox
Code for a domain that allows a protein to bind to DNA and function as a transcription regulator
highly conserved
What percentage of the genome is estimated to contain functional elements?
80%
Why is it harder to sequence eukaryotes than prokaryotes?
Eukaryotes have more noncoding sequences
Introns and other shit
Example of nonindentical genes
Hemoglobin
Fetal and adult are different
Difference between STRs and transposable elements
STRs are clustered one after the other
Transposable elements are scattered throughout the genome
What can mutations create?
- Pseudogene
- Gene with new function
- Gene family with distinct but related members
Homeotic genes
Selectively expressed as the organism develops
Homologous genes in different species
Means they descended from a common ancestor
Evidence that we share common evolutionary history with Neanderthals
Small number of modern homo sapiens have Neanderthal sequences (lexie’s cousin)
Homeotic genes
Encode transcription factors that control the expression of genes responsible for specific anatomical structures
Genomic hot spots
Areas that have the most disease, mutate the most, most often correspond with chromsomal breakpoints
(3)
Why is it unwise to try to relate an organism’s complexity with its size or number of cells?
Single celled organism still has to conduct complex life functions like the large celled organism
How do multigene families arise?
Duplication
