cell anatomy Flashcards
definition of a cell
the basic structural unit of all living organisms
what are cells composed of?
water(80%), protein, lipid, carbohydrate, inorganic
what is the plasmalemma
outer membrane of a cell
-biomolecula player of amphipathic phospholipids
what is the role of the cytoskeleton?
-determines shape and fluidity of cell
→Allows movement of organelles and of the cell itself
→Gives shape and can change shape
what is the cytoskeleton composed of>
thin/intermediate filaments and microtubules
what is the role of the plasma membrane
separate cytoplasm from outside environment
what is the permeability of the plasma membrane
selectively permeable (high to water/small hydrophobic molecules) (low to charged ions)
what are the organelles of the cell
-nucleus
-mitochondria
-rER
-sER
-Golgi apparatus
-lysosomes
-inclusions
what are inclusions?
-components synthesized by the cell itself
-not apart of metabolic activity
-example: adipose tissue
function of the nucleus
contains genetic information
function of the mitochondria
energy (ATP) production
function of rER
protein synthesis
function of sER
cholesterol and lipid synthesis/detoxification
function of golgi apparatus
modification and packaging of secretions
function of lysosomes
hydrolytic enzymes for intracellular digestion
what type of proteins are cytoskeletal proteins?
filamentous cytosolic proteins
what are the 3 classes of filaments
-microfilament
-intermediate filament
-micortubule
what are microfilaments?
-composed of 2 actin strands
-involved in cellular movement, cell division and muscle contraction
-7nm
what are intermediate filaments?
-6 proteins that bind intracellular elements together and to the plasmalemma
-Gives strength to structure of cell
-10nm
-These classes are used in pathology to identify tumour origins
-example: astrocytes
what are microtubules?
-hollow and composed of alternating alpha and beta tubulin subunits that can be assembled or disassembled
-microtubules are important in cilia, flagella and the mitotic spindle
-microtubules act as the highway network of the cell as proteins Dynein and kinesin attach and move along them
-25nm
what is kinesin?
-kinesin is an ATPase that moves toward the outside of the cell
what is dynein?
-dynein is an ATPase that moves toward the cell centre
why are kinesin and dynein important?
important in the movement of proteins
what is cyostol?
Solution of proteins, electrolytes and carbohydrates which the cellular components are embedded
what type of chromosomes does the nucleus contain?
-Euchromatin
-Heterochromatin
what is euchromatin?
DNA is more dispersed and undergoing transcription
what is heterochromatin?
DNA highly condensed and not undergoing transcription
which RNA synthesis happens in the nucleus
-mRNA
-tRNA
which RNA synthesis happens in the nucleolus
rRNA
what are the 2 types of golgi network?
-cis
-trans
what does the cis golgi network do?
transports away from nucleus towards outside of cell
what does the trans golgi network do?
transports towards nucleus
what are intracellular junctions?
things that connect cells to other cells into a functional unit, mainly in epithelial cells
what are the 3 types of intracellular junctions?
-occluding/tight (form diffusion barrier), -anchoring (provide mechanical strength)
-communicating (allow for movement)
what are occluding/tight junctions?
- Links cells to form a diffusion barrier and prevents diffusion
- Water tight seal to prevent water flowing between cells (bladder/kidney)
what are anchoring junctions?
Provides mechanical strength “cells adhere to one another”
-prevents separation
what are desmosomes (macula adherents)?
link sub membrane intermediate filaments of adjacent cells (macula adherents
what are communicating (gap) junctions?
Allow movement of molecules between cells (selective diffusion- like a tunnel)
-made up of connexins→ allows rapid communication
what are connexins and what do they do?
(transmembrane proteins)
-allows ions and cytokines to pass between cells→ allows rapid communication
what is a junctional complex?
several types of junctions found in certain epithelial cells
how can materials move across the cell?
-diffusion
-transport proteins (pumps or channels)
-vesicles (requires ATP)
what are the 2 types of vesicular transport?
-endocytosis
-exocytosis
what is endocytosis?
-material from outside the cell is invaginated through the membrane and the endocytotic vesicle(endoscope) buds into the cell
-(this process is receptor mediated)
what is exocytosis?
opposite of endocytosis, materials leave the cell
what is phagocytosis
bacteria binds to cell surface, cell engulfs it to form phagosome, binds with lysosome producing a phagolysosome
