Cell Organelles Flashcards
What are the 2 components of the cytoplasm?
- The cytosol (intracellular fluid)
- The organelles
What is Cytosol?
The site for ezyme controlled reactions. (conventional cytoplasm)
-55% of cell volume and is 70-90% water
- Contains dissolved ions, glucose, amino acids, ATP, lipids and waste products
What is the cytoskeleton and its function?
Network of protein filament extending throughout cytomplasm
- Helps maintain shape and internal organisation
- Provides mechanical support - for devision and movemnet
What are the 3 main types of cytoskeleton?
- Microfilaments
- Intermediate filaments
- Microtubules
What are microfilaments?
Filaments that surround the edge of the cell - help generate movement
ACTIN and MYOSIN
create microvilli eg in small intestine
Give 3 examples of Intermdediate filaments and their function
Keratin, vimentin and lamin
- Strong structures in parts of cell subject to mechanical stress.
They stabalise positions of organelles
What are microtubules?
Long, unbranched hollow tubules made from tubulin that form in the centrosome, then radiate outwards
- Help with cell strength, shape and movement of organelles . Eg vesicles and division
Provide structure to flagella. e.g. spermatozoa
What is the centromere and where is it found?
Main microtubule organising centre and regulator of cell cycle progression. Grows miotic spindle during cell division
Found near nucleus
What does centromere consist of?
2 centrioles;
Cylindrical structures - 9 clusters of microtubule triplets, both at right angles to each other
What surrounds the centrioles and what does it consist of?
Pericentriolar material
Consists of
numerous rings of tubulin
When does number of centrosome change?
Non dividing cells - single centrosome
Begins to divide - centrosome replicates early in process
The spindle apparatus forms after centrosome replication
What is cillia?
Numerous, short hair like projections.
These transport fluid along cell surfaces
What do female smoker have increased risk of?
Ectopic pregnancy - due to destroyed cillia in uterus
What are flagella?
Similar structures to cillia but longer and often found singularily
Eg. sperm tail
What is the endoplasmic reticulum?
Network of membranes in the form of flattened sacs and tubules extending from the nuclear envelope into the cytoplasm
What is Rough ER?
Structure where proteins made by ribrosomes enter for sorting and processing
What are ribrosomes?
Sites of protein synthesis
-Rich in RNA and contain >50 proteins each
Can be found free in cytoplasm, in mitochondria or on ER
What is the Smooth ER?
Extension of rough ER without ribrosomes.
- synthesise fatty acids and steriods (eg. estrogens and testosterone)
- Releace glucose in liver
- detoxify lipid soluble drugs eg. alcohol and pesticides
- store Ca2+ ions in muscles
Give an example of a fdrug that changes rough ER in liver cells when used repeatedly
Phenobarbital - more needed to feel affect as more smooth ER
What is the golgi complex?
3-20 membranous cisternae (sac like structures) with bulging edges arranged in a stack
Entry cis face faces ER
Exit trans face faces plasma membrane
What is the function of lysosomes?
Digestion of substances entering the cell, worn out organelles (autophagy) and entire cells (autolysis)
What is Tay - Sachs disease?
Inherited condition affecting children that casues seisures, muscle regidity and become blind.
Death is often before age 5
What causes Tay - Sachs disease?
Mutation of lysomal enzyme Hex A
Hex A is meant to break down GM2, which is prevelant in nerve cells.
Absence of Hex A means GM2 builds up and destroys nerve cell function
What are peroxisomes?
Simar structures to lysosomes but smaller
- Contain oxidases
- Metablosise amino acids and fatty acis
- Oxidise toxic substances such as alcohol - lots in liver
- Contain enzyme catalase to protect against toxic hydrogen peroxide (made in oxidation reactions)
