Cells and organelles Flashcards
Definition of a cell
Semi independent, living unit within body (completely independent in unicellular)
Site of metabolism mechanisms, growth, replication
Made up of aqueous solution of organism molecules, membrane bound
Definition of an organelle
Subunit within cell
Defined structure w specific integrated activities
Not all are membrane bound
Definition of a tissue
Organized assembly of cells and extracellular products
Carry out similar, coordinated activities in body
Definition of an organ
Assembly of tissues, coordinated to perform specific body functions
Definition of a system
Assembly of organs w specific, related activities, sharing regulatory influences
Can be a diffuse functional network of cells situated in many body parts, sharing specific activities
Definition of a prokaryote
Unicellular organism, circular strand of free chromosomes
No membrane bound organelles
Definition of a eukaryote
Uni/multicellular, chromosomes in nucleus, normally have cytoplasmic, membranous organelles, DNA divided into many linear chromosomes, vary from cel to cell within organism
Includes complex organisms
Definition of a virus
Assemblage of DNA/RNA and proteins, parasitic of prokaryotes/eukaryotes
Invade cell, hijack protein synthesis to make more viruses
Only operate in host cells, no plasma membrane
What are living organisms made up of
Cells
What are higher organisms considered
Communities of vells
What can individual cells within communities do
Peform specialized functions
What is not considered a cell
Virus
Genetic structure of prokaryotes
Single, circular chromosome In nuclei No nucleus No histones Has plasmids
Genetic structure of eukaryotes
Paired chromosomes Membrane bound nucleus Has nucleolus Has histones Has extrachromosomal DNA in mitochondria and plasmids
Intracellular structures of prokaryotes
No mitotic spindle No sterols Internal membrane only in photosynthetic organisms No ER Respiration at cell membrane No golgi No lysososomes No peroxisomes 70S ribosomes No cytoskeleton
Intracellular structures of eukaryotes
Has mitotic spindle Has sterols Has membrane bound organelles Has ER Respiration at mitochondria Has golgi Has lysosomes Has peroxisomes 80S ribosomes in cytoplasm, 70S in mitochondria Has cytoskeleton
Extracellular structures of prokaryotes
Peptodoglycan, LPS, teichoic acid cell wall
Has capsule/slime layer
No cilia
Has pili and flagella
Extracellular structures of eukaryotes
Most don’t have cell walls, chitin in fungi
Most don’t have capsules or slime layers, pellicle/shell in some parasites
Cilia in some cell types
No pilli
Flagella in some cell types
Reproduction of prokaryotes
Binary fission
Asexual
Reproduction of eukaryotes
Mitosis/meiosis
Asexual/sexual
What is cell theory
All living things are made from cells
Arise through division of preexisting cells
Subcellular resolution and microscopes
Only EM can reveal subcellular details
TEM, see ultrastructure, electrons go through specimen
SEM, see cell surface, electrons scattered off cell surg=face by heavy metal coating of Au
Downfalls of EM
Elaborate prep needed
Only dead cells can be viewed
What limits the max size of a cell
Diffusion<50um = efficient
As cell size increases, V:SA decreases
How do specialized cells overcome the limitations of diffusion
Thin processes
Giant multinucleate cells
Gap junctions
Whats a thin process
Directed transport of substances around cell via, cytoskeleton (neurons, oligodendrocytes)
Giant multinucleate celles
Gene expression occurs in more than 1 place (skeletal muscle cells)
Gap juctions
Channels between cells, allow movement of substances between cells
Purpose of membrane bound cellular organelles
Allows specialized environments within
Different functions operate under different conditions (pH)
Single cell can have many functional compartments
Protein filaments that make up the cytoskeleton
Actin -thinnest muscle fibres Microtubules -thickest, pull daughter cells apart Intermediate filaments -mechanical strength of cell
Function of cytoskeleton
Contribute to mechanical strength, control shape, drive, guide material movement
What is the cytosol
Aqueous environment in plasma membrane
What is the cytoplasm
Cytosol + organelles
Size of nucleus
Largest organelle
3-10um
Function of nucleus
Contains packaged genetic material
DNA organized as chromosomes
Chromatin= complex of DNA/histone and non histone proteins which form nucleosome
When cell not dividing, uncondensed chromatin
Function of nucleolus
Site of rDNA transcription, assembly site of ribosomes
How many membranes does the nuclear envelope have
Double membrane
Function of nuclear pores
Allows transport in and out of nucleus
Function of SER
Biosynthesis of membrane lipids, steroids
Start of N linked glycosylation, detoxification of xenobiotics
Function of RER
Covered in ribosomes, translation, proteins for secretion/insertion into cell membrane
Proteins folded, disulphide bridges
Vesicles bud from RER, sent to golgi
Structure of golgi body
4-8 stacks of cisterna, membrane bound channels
Modifies proteins from RER via vesicles
Modifies N linked carbohydrates
Glycosylation of O linked carbohydrates and lipids
Synthesis and package secretory materials
Direct new proteins in vesicles to compartments
Transport membrane lipids around cell
Create lysosomes
Structure of secretory vesicles
Bud off form golgi
Function of secretory vesicles
Fuse with inner surface of plasma membrane, exocytosis of hormone, neurotransmitters
Function of peroxisomes
Detoxification Oxidation of VLCFA Contains oxidative enzymes, form H2O2 Contains enzymes that neutralize H2O2, form H2O and O2 Site of phospholipid synthesis
Structure of lysosomes
> 50 types of hydrolytic enzymes for all major macromolecules, low pH needed for acid hydrolysis
Involved in organelle turnover/autophagy
Uses ATP to pump H+ into lysosome
Size of mitochondrion
0.5-2um
How to synthesis mitochondrial proteins
Have mitochondrial DNA
Function of mitochondria
Oxides sugars and generate ATP in Krebs
Structure of mitochondrion
Have double membrane
Cristae increase SA:V
Krebs cycle enzymes/ETC in different parts of the membrane structure
Size of a lysosome
0.2-0.5um
Size of peroxisome
0.2-0.5um
