1.2 ultrasound of cells Flashcards
1
Q
compare electron microscopes and light microscopes
A
electron have a much higher resolution that light
- resolution of fine features dependent on wavelength of light used
- lower wavelength, finer level of detail
- light microscopes constrained by wavelength of visible light [approx 400 – 700 nm]
- electrons have smaller wavelength [2 – 12 picometres, where 1 picom = 1 x 10^-12 m]
- light microscopes accurate to abt 1000x mag
- cellular components within organelles usually not resolvable using light micro [mitochondria can] but can be w electron micro
2
Q
types of electron microscopes
A
scanning electron microscope
- electrons focused on surface of specimen to provide 3-dimensional image
transmission electron microscope
- electrons focused through sample; used to study internal structure of cells
3
Q
what is the 3 domain system of biological classification
A
- archaea – “primitive” domain containing mainly microorganisms with unique properties [e.g. microorganisms found in deep sea vents, hot springs, or produce methane in anaerobic conditions, etc]
- bacteria
organisms under these 2 are considered prokaryotes - eukaryota [goes on to 4 kingdoms of protista, fungi, plantae and animalia]
4
Q
cell structure of prokaryotes
A
- genetic material not encased within a membrane, coiled into region known as nucleoid
- unlike eukaryotic, do not contain any membrane-bound organelles
- cytoplasm encased within plasma membrane
- only 1 chromosome, in the form of circular dna
- may contain plasmids, accessorial extra-chromosomal dna that replicates independently from chromosome
- mesosomes may form from infolding of cell surface membrane to increase surface for activities like cellular respiration
- most bacteria feed via extracellular digestion, where enzymes are secreted out of cell and nutrients absorbed into cell, with all transport regulated by cell surface membrane
- many prokaryotes possess cell walls that maintain cell shape, and are commonly made up of peptidoglycans
- many prokaryotes possess slime layers that have some defense function and aids in formation of biofilms
5
Q
how do prokaryotes divide? w elaboration
A
binary fission
- dna replicated in semi-conservative manner
- 2 dna loops attach to cell surface membrane
- cell surface membrane elongates and divides into 2 cells (cytokinesis)
- 2 daughter cells genetically identical
6
Q
cell struture of eukaryotes
A
- dna encased within double membrane nuclear envelope
- cytoplasm found between nuclear membrane and cell surface membrane
- membrane bound organelles aid in compartmentalisation
7
Q
let’s talk about nucleus [genetic control]
A
- largest and most visible organelle within cell
- storage location of genetic material in form of chromosomes (dna wound around histone proteins)
- nucleoplasm: material within nucleus
- encased within double membrane known as nuclear envelope
- presence of pores in nuclear envelope to regulate entry and exit of substances like mRNA
- nuclear membrane connected to system of membranes known as endoplasmic reticulum
- nucleolus: dense region within nucleus responsible for ribosomal rna production
- (summary) dna replication, rna synthesis, assembly of ribosomal subunits (in nucleoli)
8
Q
let’s talk about ribosomes [genetic control]
A
- primarily involved in protein production / polypeptide synthesis
- made up of ribosomal rna produced in nucleolus of nucleus
- quantity of ribosomes found in cell dependent on amount of proteins that cell must produce
• Secretory cells that secretes hormones like the exocrine gland cells of the pancreas contains large numbers of ribosomes - either membrane bound or free floating
• Free ribosomes are found floating in the cytoplasm and are usually involved in the production of proteins needed within the cytoplasm
• Bound ribosomes are mainly found on the rough endoplasmic reticulum and are associated with proteins packaged in other organelles and exported out of the cell
9
Q
what is the endomembrane system?
A
includes:
- nuclear envelope
- endoplasmic reticulum (er)
- golgi apparatus
- lysosomes
- vacuoles
- plasma membrane
10
Q
let’s talk endoplasmic reticulum [manufacturing, distribution, and breakdown]
A
rough
- contains ribosomes (membrane bound) attached to membrane
- involved in production of polypeptides that usually will be transported via vesicles to the Golgi Apparatus for further packaging and subsequently exported out of the cell
- process: mrna goes through ribosome, codes for polypeptide, sugar chain attaches to form glycoprotein, transport protein buds / pinches off to carry secretory protein away
- (summary) synthesis of membrane lipids and proteins, secretory proteins, and hydrolytic enzymes; formation of transport vesicles
smooth
- lacks associated ribosomes
- involved in other metabolic processes including the production of enzymes necessary to produce lipids and steroids, or enzymes that processes drugs and alcohol
- (summary) lipid synthesis; detoxification in liver cells; calcium ion storage
11
Q
let’s talk golgi apparatus [manufacturing, distribution, and breakdown]
A
- (summary) modification and sorting of macromolecules; formation of lysosomes and transport vesicles
- involved in further processing and packaging of molecular products of the cell
- folds and packages polypeptides together to form functional proteins
- molecular products travel via vesicles to one side of the Golgi apparatus
- products are processed, modified and processed as they travel to the other side of the Golgi apparatus
- vesicles containing the final products from the Golgi apparatus pinch off and travel to other organelles or the cell surface membrane for exocytosis
12
Q
let’s talk lysosomes (in animal cells and some protists) [manufacturing, distribution, and breakdown]
A
- (summary) digestion of ingested food, bacteria, and a cell’s damaged organelles and macromolecules for recycling
- membrane bound sacs containing digestive enzymes
- originated from the Golgi apparatus, with the original polypeptides forming the enzymes produced in the rough ER
- presence of membrane helps to isolate the digestive enzymes from rest of the cell and cytoplasm to prevent auto-digestion (unless triggered to do so in some cells)
- needed for the digestion of food molecules in food vacuoles taken in via phagocytosis
- used to digest worn out organelles in the cell for nutrient recycling
- some can fuse with cell surface membrane to lead to exocytosis (secretion) of enzymes out of the cell
13
Q
let’s talk vacuoles [manufacturing, distribution, and breakdown]
A
- large vesicles with a diverse range of functions
- contractile vacuoles are found in many protists that are able to mechanical pump out water for osmoregulation
- large central vacuole found in plant cells help in osmoregulation by buffering changes to water potential of plant cytoplasm
- food vacuoles are found in many cells to envelope food particles taken in via phagocytosis
- many plant cells contain vacuoles that store toxins or pigments
- (summary) digestion [food vacuole]; storage of chemicals and cell enlargement [central vacuole]; water balance [contractile vacuole]
14
Q
what sets mitochondria and chloroplasts apart from the rest?
A
- double membrane
- not part of the cellular endomembrane system
- have own chromosomes (circular DNA)
15
Q
let’s talk mitochondria [energy processing]
A
- found in almost all eukaryotic cells and are responsible for cellular respiration to produce energy in the form of Adenosine Tri-Phosphate (ATP)
- double membrane – smooth outer membrane and an inner membrane folded inwards to form cristae
- 2 compartments – mitochondrial matrix and intermembrane space
- mitochondrial matrix contains:
• enzymes that catalyse cellular respiration processes
• ribosomes
• mitochondrial DNA - folding of cristae increases surface area for reactions to occur that synthesizes ATP
- (summary) conversion of chemical energy in food to chemical energy of ATP
