Ch 1 Flashcards
Plasma membrane functions are carried out by ____
Bound transmembrane proteins
Cell to cell communication uses chemical messengers systems that ____into ___fluid
Release secretions into extra cellular fluid
The process to generate membrane potential is
Diffusion of current carrying ions
What is the main difference between smooth muscle vs skeletal muscle?
SM have dense bodies attached to actin filaments
What is the role of rRNA in the nucleus?
Provide a site for protein synthesis
Defective sperm motility is secondary to which cellular component?
Microtubules
Which cellular transport mechanism required the most energy?
Vesicular transport
Desmosomes role in cells?
Forms junctions at epithelial cells
What percentage of human genome are protein encoding?
1.5%
What percentage of non coding proteins regulate coding regions?
80%
Central area of chromosome is called — and distal area is called —
Centromere
Telomere
What is the role of centromere? 2
Spindle apparatus attachment
Maintain heterochromatin
What are single nucleotide polymorphisms (SNP)?
Variant in single nucleotide position and are almost always bialleleuc eg one base different
Occurs mostly in non coding region (only 1% in coding region)
What is copy number variations (CNV)?
Genetic variations consisting of different number of large stretches of DNA eg deletion, duplication
What is epigenetics?
Heritable changes in gene expression that are not caused by variation in DNA sequence
What is a nucleosome?
DNA segment of 147 base pairs long, wrapped around central core protein (histone)
Inactive dense chromatin is called
Heterochromatin
Open, active chromatin is called
Euchromatin
What happens to chromatin during histone acetylation?
Opens up so transcription can happen (methylation condenses and inhibits transcription)
Which residues can be methylated? 2
Lysine
Arginine
What is the role of micro RNA (miRNA)?
Do not encode proteins, they modulate translation of target mRNA
Post transcription silencing of mRNA genes
What is the role long noncoding RNA (LC RNA) 4
- Gene silencing: restricting RNA polymerase leading to physiologic X chromosome inactivation (bind TF)
- Enhancer: expansion of transcription via gene promoters (promote TF)
- Stabilise protein complexes for gene expression
- Facilitate histone/DNA modification
What is the role of free ribosomes?
Cytosol protein synthesis
What is the role of smooth ER?
Steroid hormone and lipoprotein synthesis
What is the role of proteosomes?
Degrade tagged/denatured cytosol proteins
What is the role of peroxisomes?
Breakdown of very long chain fatty acids; generates H2O2
What are components of the cell cytoskeleton? 3
Actin
Keratin (intermediate filament)
Microtubules
What is the role of mitochondria? 4
- Generate ATP (Oxidative phosphorylation)
- Source of metabolic intermediates
- Synthesis of macromolecules eg heme
- Regulate apoptosis (intrinsic pathway)
What is the role of endosome?
Intracellular import and export out of cell
What is the cell membrane made of?
Lipid bilayer (hydrophilic head faces inside (later 1) and outside (later 2)
Which phospholipids face outside?
Phosphatydyl choline (PC)
Sphingomyelin (S)
Glycolipids (GL)
Inositol and cholesterol (both sides)
Which phospholipids on cell membrane are involved with eat me signal?
Serine
Which phospholipids on cell membrane are involved with serum cell integration? 2
Glycolipids and sphingomyelin
Which glycolipids form ‘lipid rafts’?
GL and S
What is the role of ‘lipid rafts’?
Maintain cell polarity
Intracellular tight junctions
What are the types of endocytosis? 2
- Caveolin mediated
- Receptor mediated
What is the role of caveolin mediated transport? 5
1.Internalisation of caveolate and bound molecules (Cellular sipping/potocytosis)
2.fusion with endosomes
3. Transmembrane delivery of folates
4. Transmembrane signalling
5. Cell adhesion (areas of lipid rafts)
Examples of receptors involved in receptor mediated endocytosis? 2
Transferrin R
LDL R
What is the coating in receptor mediated endocytosis?
Clathyrin
What is the role of clathyrin in receptor mediated endocytosis?
Formation of vesicles ‘clathyrin coated vesicle’
What is transcytosis?
Movement of endocytosis vesicles from apical surface to basal surface eg ingested ab in mother’s milk
What are the function of actin filament? 3
Vesicular transport
Epithelial barrier regulation
Cell migration
What filament/protein is the most abundant in cell cytosol?
G-actin
What is formed when G-actin polymerized?
F-actin
What is actin treadmilling?
F-actin: Subunits get added to (+) subunit (subtracted from (-) subunit)