Slide Set 2 Flashcards
Proteins
- enzymes
- transport proteins
- form structural skeleton
- specific & variable
- structure encoded in dna
The 2 stages of protein synthesis
- Transcription (DNA-RNA)
2. Translation (RNA-protein)
Genes are tightly coiled with histones, what removed the histone revealing promoter segment?
enzymes
Transcription
- forms messenger RNA
- mRNA transports DNA from nucleus OUT to cytosol
Translation
mRNA (in cytoplasm) > ribosome > tRNA transfers amino acids to mRNA (anticodon) > peptide bonds are joined
- T A C C C T C A A
- A U G G G A G U U
- U A C C C U C A A
- met gly val
- template strand
- mRNA strand (U replaced T)
- tRNA strand (U replaced T)
- Amino acid strand
molecular genetics
study of how genes are turned on and off and how they affect phenotype
Real DNA hero
Rosalind Franklin, not Watson & Crick
Where is chromatin
In nucleus (part of supercoiled region of chromosome)
Nucleosome
- DNA + Histone proteins (H2A/H2B/H3/H4)
- repeat to make chromatin
Genes are on or off in
- euchromatin
- heterochromatin
- ON
- OFF
__ copies DNA sequence to produce mRNA
DNA POLYMERASE
DNA helicase : RNA polymerase : RNA nucleotides (Uracil instead of Thymine)
- unwinds DNA
- binds and recognises start site
- base pair with DNA
=mRNA chain is formed
In case of protein coding DNA, transcription is the beginning of the process that ultimately leads to _ of the genetic code (via the _ intermediate) into a function _ or _.
translation
mRNA
peptide
protein
Promoter regions
- DNA sequences
- define where beginning of transcription begins
- are upstream or at the 5’ end of the transcription initiation site
What binds to promoter regions?
TRANSCRIPTION FACTORS and RNA POLYMERASE, they initiate transcription
Direction of transcription
5’—-3’ (coding strand)
3’—-5’
DNA is antiparallel
CREM
cAMP response element modulator
is a transcription factor
binds to CRE in promoter region
What doesn’t occur in absence of CREM?
spermiogenesis
What are the 2 types of transcription factors
- gene-specific transcription factor (activate specific genes)
ex: estrogen receptor - general transcription factor (activate all genes)
What are the 2 types of transcription factors
- gene-specific transcription factor (activate specific genes)
ex: estrogen receptor - general transcription factor (activate all genes)
Alternative splicing
= method of processing mRNA
- enzymes clip out segment of mRNA (the introns)
Introns vs Exons
Introns : noncoding segments
Exons : genes that encode protein, express
Site of transcription
nucleus
Site of translation
cytoplasm
What are epigenetic mechanisms affected by?
Development Environmental chemicals Drugs, pharmaceuticals Aging DIet
What is an epigenetic factor found in some dietary sources?
methyl group
it can activate or repress genes
epigenetics
is the study of heritable phenotype changes that do not involve alterations in the DNA sequence
housekeeping genes
genes always expressed in cells
Looking for proteins by Western blot
CREM runs at 34Kda
What silences a particular gene?
siRNA
2 types of membrane transporters
- channel proteins (gated, open)
- carrier proteins (uniport, symport, antiport)
The Na+/K+ pump shows __ active transport
primary
uses ATP
The sodium/glucose pump shows __ active transport
secondary
uses electrochemical gradient
Epithelia transport is either __ or
leaky (capillaries)
tight (kidney)
Symptoms of cystic fibrosis
- chronic cough, diarrhea
- runny nose
- salty skin
Pathophysiology of cystic fibrosis
defective epithelial ion transport
Systems affected by cystic fibrosis
abnormal transport of chloride and sodium across the epithelium in all exocrine tissues (leaves thick viscous secretions in lungs, pancreas, liver, intestine).
Increased salt content in sweat gland secretion
Genetic & molecular causes of CF
- Faulty gene on chromosome 7
- malfunction of gene coding for CFTR (transmembrane conductance regulator), leads to defective cAMP-activated chloride and sodium channel that is present on the surface of many types of epithelial cells
- NaCl trapped in the cull which pulls water in (hypertonicity) and dehydrates mucus
How is homeostasis altered in CF
High levels of chloride and salt pulls water iINSIDE, causes dehydrated mucus (thick mucus is not broken down by water)
treatments when CF
- antibiotics
- airway clearnance therapy
- bronchial dilators
- vitamin supplements
- enzymes to aid digestion
Structural proteins, enzymes, membrane receptors proteins, transporters are all :
membrane proteins
Endocytosis
The plasma membrane “traps” some extracellular marital and brings its into the cell in a vesicle
Phagocytosis
- cell eating
- large particles engulfed by plasma membrane, enter in vesicle that fuses with the lysosomes
Pinocytosis
- cell drinking
- fluid and the substances dissolved in it enter the cell
- is non selective
