Cell And Organelles Flashcards
Unicellular organisms
Carry out all necessary functions in one cell
Multicellular organisms
Cells which are specialized for particular function
Eukaryotic cell has that prokaryotic does not have
1- presence of nucleus
2- extensive use of internal membrane
3- complex cytoskeleton
4- Endocytosis and exocytosis
Nuclear envelope
Two membrane
1- inner membrane: define nucleus
2- outer membrane: contiguous with ER
Nuclear pores
Fuse two membranes
Transport between cytoplasm and nucleoplasm
DNA in nucleus is organized into ———
Chromosomes
ER
Endoplasmic Reticulum
ER consist of
1- tubular membrane
2- flattened sacs — cisternae
Internal space of ER is
Lumen
Cisternae vs cristae
Cisternae — ER
Cristae — mitochondria
ER kinds
- smooth
- rough
RER
Critical starting point of proteins biosynthesis
-cytoplasmic side: have ribosomes
- ribosomes synthesis polypeptide
- most membrane lipid are synthesized here
SER
-No role in protein synthesis
-Synthesis of lipid and steroid hormones
-Detoxification
Specialized smooth ER
Sarcoplasmic reticulum
: storage and release calcium
Golgi entry side
Cis Golgi
Golgi complex
Accept transition vesicles from RER that enter cis golgi ( faces RER)
Glogi functions
1- processing and packaging secretory proteins
2- complex polysaccharides synthesis
In golgi proteins/lipids are ———
Glycosylated
Lysosomes
1- digestive organelles
2- single membrane
3- store hydrolases
Hydrolases
- synthesized inER
- transport to golgi and packaged into vesicles
Hydrolases function
- ph activated
- seaqestered
What maintain low internal ph in lysosome
ATP-driven H+ pump
What protect inner side of lysosome from digesting
Special carbohydrate coating on inner side
Lysosomal membrane contains transport proteins that carry———
Product of macromolecules digestion to the cytosol for reuse
Degradation pathways utilizing lysosome
1- Endocytosis
2- Phagocytosis
3- Autophagy
Materials to be exported from cell are packaged in ——— by ———
1- secretory vesicles
2- golgi complex
Secretory vesicles after releasing from golgi
Move to plasma membrane
Fuse with it —— Exocytosis
Release material outside of the cell
Endomembrane system
ER
Golgi
Vesicles
Lysosome
Endomembrane system responsible for
Trafficking substances through the cell
Exocytosis
- proteins leave the cell
- moleccules added to plasma membrane
Endocytosis
- cellular uptake of particles
- nutrients, growth factor, membrane repairs
Protein synthesis pathway
RER
SER
Cis golgi
Trans golgi
Secretory vesicles OR lysosome
Exocytosis
Trans golgi to cis golgi transport
Golgi to ER transport
Transport back due to golgi/ER needs
Peroxisomes
-single membrane
-not part of Endomembrane system
-specially inmliver and kidney cells
-FUNCTION: detoxify harmful compounds
Peroxisomes vital role in animals
Oxidative breakdown of fatty acids, especially longer fatty acids (fatty acids mainly break down in mitochondria but it can’t oxidize >12 carbons)
Oxidases
Remove hydrogen atoms from specific organic substances
H2O2 is broken by
Catalase
Peroxisomes can
Generate and degrade H2O2
Mitochondria has
2 membrane
3 regions
Mitochondria membranes
-outer membrane: relatively permeable, contain porins, free movement small molecules and ions
-inner membrane: highly permeable, permeability barrier to most solutes, folded into cristae(interior of mitochondria), respiratory proteins are embedded the inner membrane
Density of cristae is related to ———
Respiration activity of a cell
Mitochondria 3 regions
- matrix: within the inner membrane, most of the enzymes, contain DNA and ribosomes
- intermembrane space: between outer and inner membrane
-intracristal space: region were protons can accumulate during electron transport
Mitochondria contain proteins
- encoded by their own DNA
- encoded by nuclear genes
Human mitochondrion genome
Encodes 5% of all RNA and proteins needed by mitochondria
** 95% comes from the cell itself
Mitochondria function
1- principle site of ATP production
2- number and location of mitochondria vary according to their role
3- tissues with high demand for ATP have many mitochondria
4- regulation if apoptosis
Chloroplast are site of
Photosynthesis
Endosymbiont theory
Mitochondria and chloroplast evolved from ancient bacteria
Similarities between mitochondria/chloroplasts/bacteria
-Resemble bacteria size and shape
-Surrounded by double membrane
-All three have circular DNA molecules
-Mitochondria/chloroplasts are sensitives to bacterial inhibitors of RNA
Vacuoles
-90% of plant cells
-fluid-filled structures
-single membrane
Ribosomes
Each species have unique type of rRNA
Very numerous
Mitochondria/chloroplasts/bacteria have same size and composition ribosomes
Cytoskeleton
- 3D interconnected microfilaments, microtobules, intermediate filaments
-FUNCTION: strength, shape, internal organization, cell movement, cell division
Extracellular matrix
Protein, glycoproteins, glycosaminoglycans
ECM is secreted and maintained by cells
ECM functions
Support
Protect
Rigidity
Substrate for motility
