Cells Flashcards
What features do both Prokaryotes AND Eukaryotes have?
Plasma membrane, DNA, ribosomes
What are Eukaryote specific features?
DNA wrapped in histones,
Nucleus contained by nuclear envelope
Contains complex membranous cytoplasmic organelles
Specialised cytoplasmic organelles for aerobic respiration
Endocytosis and Exocytosis
Gene diploidy
What is Euchromatin and Heterochromatin
Euchromatin is ‘activated chromatin’, Heterochromatin is ‘inactivated’
What mutations lead to cancer?
sON divide signals
sOFF don’t divide signals
loss of correction mechanism on DNA replication
loss of escape mechanism from cell division
loss of limit on number of times a cell can divide
loss of control keeping within tissue boundaries
ability to evade body defence mechanisms
ability to recruit blood vessels t growing tumour
ability to migrate into blood stream or lymph tissue
ability to establish tumours in the wrong tissue (metastasis)
What are the main functions of blood?
Transport Connective tissue Heat distribution Haemostats Homeostasis
What is the difference between plasma and serum?
Plasma is the fluid component of blood
Serum is plasma without the proteins
How do erythrocytes transport O2?
Oxyhaemoglobin
Describe the negative feedback mechanism that seeks to rectify low blood O2
Low O2 > kidney releases erythropoietin > bone marrow produces more erythrocytes > increase in blood Hb > Increase in O2
What are reticulocytes, and what are they indicative of?
They are precursors to erythrocytes and high levels are diagnostic of anaemia or chemotherapy
What is the lifespan of an erythrocyte? How are they removed?
120 days by the reticulo-endothelial system (phagocytic macrophages in the spleen)
What are normal [Hb] parameters?
135-165(M) 115-145(F)
What are normal [RBC] parameters?
- 4x10^-12/L(M)
4. 8x10^-12/L(F)
What are normal haematocrit parameters?
- 4-0.54(M)
0. 35-0.47(F)
Define anaemia
Low blood haemoglobin concentration
What are the three types of anaemia and why are they caused?
Microcytic (small MCV): iron deficiency due to slow bleeds, cancer, infection, parasite
Normocytic (normal MCV): acute blood loss
Macrocytic (large MCV): fewer RBC caused by folic acid deficiency (Vitamin B12 prevent folic acid actions as well)
What are the different types of leukocyte (and their relative percentages) ?
Neutrophils (40-75%) Lymphocytes (20-45%) Monocytes (2-10%) Eosinophils (1-6%) Basophils (<1%)
What is raised/low levels of leukocytes called? What does it show?
Leukocytosis = Raised; Infection, cancer Leukopenia = Low; HIV, chemotherapy
What cells are platelets derived from?
Megakaryocytes
What do platelets form when activated?
Filopodia
How are platelets activated?
- Collagen normally found in vessel walls
- Thrombin-coagulation cascade
What do phospholipids form when suspended in water?
Micelles
Why can phospholipids be described as amphiphilic?
They contain both polar and non-polar groups
What are the components of a phospholipid?
Glycerol attached to a phosphate group and two fatty acid tails. There is also an anionic or cationic group. The phospholipid must be net anionic or neutral.
How are membranes asymmetrical?
Extracellular side populated with neutral phospholipids and glycolipids.
Membrane facing cytosol tend to have phospholipids with a negative charge, giving that side a net negative charge.
How is membrane protein movement contained?
Intracellular actin cytoskeleton fences
What are lipid bilayers permeable to?
- Small uncharged molecules
- Water molecules
- Lipid soluble molecules
What are lipid bilayers NOT permeable to?
- Ions
- Small hydrophobic molecules
- Macromolecules
What is the lipid/protein composition percentages of the following membranes:
- Myelin sheath
- Plasma membrane
- Inner mitochondrial membrane
Myelin sheath - 80% lipid, 20% protein
Plasma membrane - 50/50
Inner mitochondrial - 25% lipid, 75% protein
What are the two types of membrane protein couple transporters?
Symporters: both molecules move in same direction (mainly with Na+ moving IN cell)
Antiporters: both molecules moving in opposite direction
What is the structure of the sodium-potassium pump?
Two polypeptide chains:
- alpha chain with 1000 aa, spanning the membrane 10 times, forming a hydrophilic pore
- beta chain with 300 aa forming a controller
What does the sodium-potassium pump transport?
2K+ inside the cell for every 3Na+ out.
How does the sodium-potassium pump work?
1) 3NA+ ions bind to protein
2) ATP phosphorylases an aspartyl residue
3) Change in conformation allows 3Na+ to dissociate from protein into extracellular fluid
4) 2K+ binds to protein
5) This causes a change in conformation leading to the hydrolysis of the aspartyl phosphate, releasing phosphate into cytoplasm
6) Channel has original shape and 2K+ forced out
What are viruses?
Obligate intracellular parasites
What are Helminth parasites?
Multicellular eukaryotes including tapeworms, flatworms and roundworms
What is the diameter of a platelet cell?
2-3 um
