Chapter 16

Gene expression is often controlled by regulatory proteins binding to specific DNA

Some stimulate transcription, while others inhibite

• Control of transcription initiation
• Positive control- increases frequency
• Activators enhance binding of RNA polymerase to Promoter in DNA

• Negtive Control- decreases frequency
• Repressors bind to operatiors in DNA.

Prokaryotic cells often respond to their enviornment by chnanges in gene expression

Genes involved in the same metabolic pathway are organized in operons

CODING REGION contains genes for the use of lactose as an energy source

REGULATORY REGION contains DNA sequences used to control transcription of coding region.

• The lac operon is negatively regulated by a represor protein
• - lac repressor binds to the operator to block trascription,
• - In the presence of lactose, an inducer (allolactose0 binds to repressor
• - Repressor can no longer bind to opperator
• - Transcripton proceeds as BASAL LEVEL.

• Glucose is preferred sugar
• - Catabolic activator protein (CAP) is an activator with cAMP as EFFECTOR
• - Level of cAMP in cells is reduced in the presence of glucose, which prevents CAP from binding to DNA

INDUCER EXCLUSION: presence of glucose inhibits the transport of lactose into the cell.

Genes for the biosynthesis of trypthon

The operon is not expressed when the cell contains sufficient amounts of tryptophan

The operon is expressed when levels of tryptophan are low

• The trp is negatively regulated
• - trp repressor bind to the opperator to block transcription

-Binding of the repressor to the operator requires a COREPRESSOR which is tryptophan

Low levels of tryptophan prevent the repressor from binding to the operator

• Control of transcription more complex
• - Eukaryotes have DNA organized into chromatin (protein-DNA)

Amount of DNA involved in regulation eukaryotic genes is much larger.

• General transcription factors
• - Bind to TATA box on promoter
• -Necessary for RNA polymerase to bind to promoter

• Specific transcription facors (activators)
• -Bind to enhancer sites on DNA
• -Increase the level of transcription

Structure is directly related to the control of gene expression

DNA wound around histone proteins to form nucleosomes

Nucleosomes may block access to promoter

• Histones can be modified
• - Correlated with active versus inactive regions of chromatin
• - Can be METHYLATED- found in inactive regions
• - Can be ACETYLATED- found in active regiond

• CHROMATIN- REMODELING COMPLEXES
• - Modify histones and DNA
• - Also change chromatin structure

• Posttranscriptional control of gene expression
• - Small RNAs- miRNA and siRNA

-Alternative splicing

- RNA editing

-mRNA degradation

miRNA gene transcribed in the nucleus

• Groomed in nucleus and again in cytoplasm
• - Ends with a ~22 nucleotide miRNA

• miRNA loaded into RISC
• - RISC uses miRNA to bind to complementary sequence on mRNA- Cleaves mRNA- inhibits translation

siRNA arise from long dsRNA

Dicer cuts yield multiple siRNAs to load into RISC

Target mRNA is cleaved

Biogenesis of both miRNA and siRNA involves cleavage by Dicer and incorporation into RISC

• Main difference is target
• - miRNA repress genes different from their origin
• - siRNAs tend to repress genes they are derived from

Introns are spliced out of pre-mRNAs to produce the mature mRNA

Detemined by tissie- specific factors that regulate how pre-mRNA is spliced

• Initiation of translation can be controlled
• - Ferritin mRNA only translated if iron is present

Mature mRNA molecules have carious half lives

Translation can be controlled by regulating any number of proteins that are required

Creates mRNA not truely encoded by genes

Involves chemical modification of bases

• Apolipoprotein B exists in 2 forms
• - One is produced by editing yhe mRNA to create a stop codon

Phosphorylation or other chemicl modifications alter protein activity

Protein degradation removes damaged or unwamted proteins

Protein produced and degraded continually

Lysosomes for nonspecific protein digestion

• UBIQUITIN for specific destruction
• - Degradation of proteins marked with ubiquition occurs at the PROTEASOME

Double birth weight between 5 and 6 months

Much weight gain is baby fat

Birth length is about 1/4 of ultimate adult height

Disproportionally large- may be a fourth to a third of body length of the baby

Arms and kegs disproportionately short until about age 6 or 7

Made up of two parts:

Ends are Called Epiphysis- one on each end of long bone

• Center or Shaft of long bone is called Diaphysis.
• In between epiphysis and diaphysis is cartilage line or "growth line".

Evaluates the right or the wrong of the situation by the consequences rather than intention.

Egocentric attitude

Moral relationship based on mutual respect

"Ill be nice to you if you are nice to me."

Realistic application- take all factors into consideration befor you judge.

Child decides what is right or wrong on the basis of what will be punished.

Live up to what is expected of you.

Good boy or girl

Principled morality- achieve the greatest good for the greatest number.

Rules should be based on mutual agreement, not blind authority.

Boys think girls feel

Lack awareness of others needs

"Right" is whatever pleases others best.

Right action takes account of self as well as others

Baby sees what he wants, makes a sound to indicate what he sees. Cargiver responds by producing the ball. Next time baby wants a ball, he will say ba. rewarded behavior will be repeated

Learning by listening- observing and imitating

This is a biologically based theory. Chomsky believed that children have an inborn capacity to learn. The innate capacitiy is called LAD ( Language Acquisition Device) road map to appropriate words.

Bothe the linguistic enviornment and the inate biological structure combines to help the child learn language

They must learn sounds of the lanuage

learning the language words

Learning the mening of words

Must learn to be able to piece together thae organization of words into sentences and connected thoughts.

Dialation and Effacement

Dilation - widening of the cervix to allow fetus to come out

Effacement- flattening or thinning out of the cervix

Presentation: Head- 95%

Breech- 3-4%

Shoulders-1%

Double shoulders- Footing-1%

Epistomy: Stitches

Examined and sent to lab for further examination

Labor and delivery should be a natural process

wrote book Birth without trama

cross blood contamination between placenta from mother and baby, treat with Rho Gam

Checks for

Heart Rate

Respiration

Reflex Irritability

Muscle Tone

Color 2 points for each 10 good to 0 bad

the most inconvience that is Having in most