Transcript Chapter 12 DNA and RNA - Northwestern High School

11.1 Gene Regulation
• Only a fraction of the genes in a cell are
expressed at any given time.
• Expressed genes are genes that were
transcribed to the RNA.
• Certain DNA sequences act as binding
sites for RNA polymerase, and start and
stop signs for transcription.
• Every cell can express different genes.
– Pancreas secretes many digestive enzymes,
amylase, that help break down starches.
Expression of this genes allows it to function.
Our marrow cells would not need to have this
protein produced.
– Morphogenesis (cell differentiation, cell
specialization)
Expression in Prokaryotes
• Operon – series of genes
• Pg 218
• E. Coli
• The lac genes are turned off by repressors
and turned on be the presence of lactose.
• What happens if there is no lactose?
• Regulator codes for a repressor
• Pg 218
• If lactose is not present – repressor is
located on the operator (preventing RNA
polymerase to transcribe.
In Eukaryotes
• TATA box – a warning to the RNA
Polymerase.
• Introns (bad) and Exons (good)
• Around 28-30 base pairs long
• Helps the Genome project
Regulation and Development
• Homeotic Gene
– Control the organs and tissues, and
determine the basic body plan of animals.
– Homeobox – a certain sequence for “hox
genes”
– Pg 224
Cancer
• Read page 225
12.1 Inheritance and Human
Genetics
• Sex Chromosomes – X or Y
– Male XY, Female XX
• Autosomes 1-22
• Germ Cell vs. Somatic Cell
• SRY – on the Y chromosome (sexdetermining region
Sex linked genes and traits
• If on the X chromosome – most females
are carriers and males express the trait
• X Chromosome inactivation in females.
Form barr bodies in females
Linked genes
• Close together and on the same
chromosome, called linkage groups
Gene Map
• Rough
estimation
Of distances
b/w genes.
In your Notes
• Write
TACAATGCTCAAACT
• 1. mRNA Strand to match
• And Decode
•
•
•
•
Replace 3rd A with a C
Now Transcribe and translate again.
What happened?
What type of mutation?
Write same DNA sequence again
• Now insert a T after the 2nd T in the DNA
strand
• What does that do to the amino acids
produced?
• What type of mutation is this?
Mutations
• Gene mutations – single gene
– Point mutation is a mistake on just one nucleotide
– Nucleotides can be deleted or inserted (pg 307)
• Frameshift mutation
This is an example of
sickle cell:
Substitution
Chromosomal Mutations
• Changes in the number or structure of
chromosomes. (locations of genes, number of
copies of genes)
– Deletion
– Duplication
– Inversion
– Translocation
– Nondisjunction (too few or too many chromosomes
Web
• http://learn.genetics.utah.edu/content/disor
ders/whataregd/
12.2
• Pedigree
– Map of generations phenotypic inheritance
– Male square, female circle
• Complex characteristics – not just genetic
but also environmental.
– Height, personality, skin color, health in
general
Multiple alleles – blood type, fur color
Polygenic – skin color, eye color
Codominance – both expressed – AB blood,
roan cow
Incomplete dominance – share
X – linked – most recessive, on X
Look at Disorders
http://learn.genetics.utah.edu/content/disord
ers/whataregd/
• Read Gene Therapy
• This will be our next chapter…..