Cells And Organelles Flashcards
What’s alopecia?
Hair loss
What’s dysplasia?
Presence of abnormal cells in a tissue, preceding cancer development
What’s a cell?
Semi-independent, living unit in which are sited mechanisms for metabolism, growth and replication. Membrane-bound aqueous solution of organic molecules
What’s an organelle?
Subunit in a cell with a specific structure, performing specific integrated activities. May be membranous or non-membranous
What’s a tissue?
Assembly of cells and their EXTRACELLULAR PRODUCTS which carry out similar and co-ordinated activities
What’s an organ?
Assembly of tissues carrying out specific and coordinated activities
What’s a system?
Assembly of organs performing specific, related activities, sharing REGULATORY INFLUENCES
OR
a diffuse network of cells in many body parts, sharing specific activities
What’s a prokaryote?
Single called organism in which chromosome lies as a circular free strand in cytoplasm, no membrane bound organelles
What’s a eukaryote?
One or more cells in which chromosomes lie in nucleus, DNA’s linear. Cytoplasmic, membrane bound organelles
What’s a virus?
Assemblage of DNA/❗️RNA❗️ + proteins, parasitic on eukaryotes/prokaryotes. Operate chemically to subvert cell’s protein manufacturing mechanism, producing viruses instead of normal proteins. Escape to infect other cells. No membrane
Differences between eukaryotes and prokaryotes in terms of genetic structures
- Genetic material
P: single circular chromosome
E: linearly in paired chromosomes - Location
P: nucleoid region
E: nucleus - Nucleolus
P: none
E: present - Histones
P: none
E: present - Extrachromosomal DNA
P: plasmids
E: mitochondria/ plasmids
Differences between prokaryotes and eukaryotes in terms of intracellular structures
- Mitotic spindle
P: absent
E: present - Plasma membrane
P: no sterols
E: has sterols - Peroxisome
P: absent
E: present - Internal membranes
P: photosynthetic organisms only
E: many - ER
P: absent
E: present - Cytoskeleton
P: absent
E: present - Respiration
P: at PM
E: mitochondria - Lysosomes
P: absent
E: present - Golgi
P: absent
E: present - Ribosomes
P: 70S
E: 80S
Differences between prokaryotes and eukaryotes in terms of extracellular structures
- Cell wall
P: peptidoglycan
E: chitin in fungal - Flagella
P: present
E: only in some - Pili
P: present
E: absent - Cilia
P: absent
E: present in some - External layer
P: slime layer
E: absent
Differences between prokaryotes and eukaryotes in terms of reproduction
- Cell division
P: binary fission
E: mitosis/ meiosis - Mode
P: asexual
E: asexual/ sexual
diff between SEM & TEM
TEM: subcellular features, electrons go through specimen
SEM: subcellular features, electrons scattered off cell surface
What’s the maximum size of a cell, and why can’t it get any bigger
Less than 50 micrometres.
Volume increases > SA
Distance of diffusion from nucleus to periphery increases, slowing rate of diffusion of waste materials, metabolites and intermediates
How do specialised cells overcome the problem of diffusion inefficiency due to size
- Multinucleation: gene expression in more than one place
- GAP junctions: movement of substances between cells
- Thin processes: cytoskeleton
What’s cytoskeleton made of? What are three types of it?
Protein filaments.
Thinnest: actin
Intermediate: mechanical strength eg keratin
Microtubules
Function of cytoskeleton
- Mechanical strength
- Shape
- Drives and guides movement of materials
Cytosol vs cytoplasm
Cytosol: aqueous environment within PM
Cytoplasm: cytosol + organelles
Function of nucleolus
Rdna transcribed, ribosome subunits assembled
SER function
- Synthesis of lipids and steroids
- Start of N-linked glycolysation
- Detox of xenobiotics
RER function
- Protein synthesis: membrane bound ribosomes synthesise proteins for secretion/ insertion into CM
- Cys-CYs bridge formation
- Vesicles bud off RER and are transported to Golgi
Golgi function
- Synthesises/packages materials for secretion
- Directs new proteins to right compartment
- Synthesis of lysosomes
- Modification of proteins:
N-linked carbohydrates
Glycosylation of O-linked carbs&lipids - Transports membrane lipids
