LEC 7 Flashcards
CELL THEORY/STRUCTURE
Cell Theory (3)
- All living things are composed of cells and cell products.
- A single cell is the smallest unit that exhibits all the characteristics of life.
- All cells come only from preexisting cells.
Eukaryotic cell (4)
- Has cell membrane
- Membrane-bound nucleus with DNA
- Cytoplasm (with gel-like fluid called cytosol)
- Membrane-bound organelles designed for specialized functions
Prokaryotic cell
- Simplest cells
- Nucleoid - DNA containing inner region (not membrane bound)
- Cell membrane & rigid cell wall
- No membrane bound organelles
- Divide rapidly
All cells do what 4 things?
- Gather raw materials
- Excrete wastes
- Make macromolecules
- Grow and reproduce
Why are all cells small?
the larger the cell gets, the more likely that its growth and metabolism will be limited by its ability to supply itself across the plasma membrane
Smaller is more efficient!!!
Microvilli
Microscopic projections that extend outwards from the cell
Increase surface area
Types of microscopes
Light microscope
Transmission electron microscope
Scanning electron microscope
Light microscope
can magnify a sample up to 1000 times
Transmission electron microscope (2)
makes 2D image of the outer surface using electrons
Can magnify up to 100,000 times
Scanning electron microscope (2)
makes the 3D image of the outer surface using electrons
Can magnify up to 100,000 times
Nucleus (2)
control centre of the cell
has most the genetic material
Parts of Nucleus (3)
1.Nuclear membrane
2. Nucleolus
3. Nuclear pores
Nucleolus (2)
Dense region inside nucleus
Components of ribosomes form here and pass through pores to enter cytoplasm
Nuclear membrane (2)
Double layer of phospholipids
Surrounds the DNA & keeps it inside the nucleus
Nuclear pores (2)
Selectively allows materials (ribosomes, proteins and RNA) to move in/out
Too small for DNA to leave through
Ribosomes def
Involved in assembling amino acids in the correct sequence (primary structure) into specific protein chains
Where are ribosomes found? (2)
- Float in cytoplasm
- Attach to the rough ER
How are ribosomes formed? (3)
- Parts of RNA and ribosomal proteins are formed
- Parts leave the nucleus via nuclear pores
- Enter the cytoplasm and are assembled into ribosomes
Where are ribosomes formed?
nucleolus
Endomembrane System (4 organelles)
- Rough Endoplasmic Reticulum (production)
- Smooth Endoplasmic Reticulum (packaging)
- Golgi Apparatus (labelling)
- Specialized vesicles (shipping)
Endoplasmic Reticulum def
Works with ribosomes to synthesize most of the chemical compounds made in the cell
Endoplasmic Reticulum structure
- Repeated folded membrane structure
- Fluid filled
- some of it is connected to the nuclear membrane
- form transport vesicles to move synthesized materials out of the cell
Endoplasmic Reticulum types
rough ER
smooth ER
Rough ER to Smooth ER
- Involved in protein synthesis (on the outside)
- Once synthesized, proteins enter the fluid-filled space of rough ER
- Proteins enter the smooth ER
Rough ER structure (3)
repeated folded
physically connected to the nuclear membrane
dotted with ribosomes
Smooth ER def
- Synthesis of macromolecules (lipids and some hormones)
Packaging centre for proteins & lipids that were synthesized by both the rough endoplasmic reticulum and smooth endoplasmic reticulum
Smooth ER to Golgi bodies
- Smooth ER sends “package” to the Golgi apparatus through vesicles (that form from membrane of smooth ER)
- Pinch off
Golgi Apparatus def
Processes and packages proteins and lipid molecules
What happens inside the Golgi body? (4)
- Enzymes refine and complete proteins
- Adds “label” that indicates where product should be sent
- Sorts and packages products
- Forms vesicles that “ship” products to their final destination
How does the Golgi body receive transport vesicles? (2 )
- Vesicles fuse with the fluid-filled membrane layer of the Golgi apparatus 2. Empty contents to the inside
Where does lipid synthesis happen?
Inside Golgi body
What are secretory vesicles made up of?
Golgi body membrane
What are secretory (exocytotic) vesicles for?
- Has products destined for export from the cell
- Release contents to the outside of the cell
How do lipids leave the Golgi body?
through vesicles
What are endocytotic vesicles for?
Enclose bacteria & raw materials from the outside of the cell and bring them inside
What do peroxisomes
do? (2)
- Vesicles that contain powerful enzymes
- Used to destroy toxic wastes produced in the cell
What kind of toxic waste do peroxisomes destroy?
alcohol
meds
drugs
What do lysosomes do? (3)
- Contain powerful digestive enzymes
- Fuse with endocytotic vesicles and digest bacteria and other large particles
- Conduct “housekeeping” tasks (lysis of anything not required)
Mitochondria (2)
powerhouse of the cell (make ATP)
cellular respiration (in the presence of O2)
Main sources to create energy (3)
- Fats
- glucose
- glycogen
How many mitochondria are in each cell?
Depends on the cell’s needs (muscle cells will have more while nerve cell mitochondria)
Mitochondria structure
- Double membrane system
- own DNA and ribosomes
Mitochondria OUTER membrane structure
smooth
Mitochondria INNER membrane structure (2)
- Deeply folded (cristae)
- Has enzymes bound to it
What happens inside the mitochondria’s INNER membrane?
Enzymes catalyze reactions to release energy
Cytoskeleton
- Helps cell membrane maintain its shape
- Support and anchors other structures within the cell
Cytoskeleton network is made up of: (2)
- Microtubules
- Microfilaments
Microtubules
tiny hollow tubes
Microfilaments
thin solid fibres
How is the cytoskeleton network constructed?
microtubules and microfilaments connect to each other and the glycoproteins in the cell membrane
Cilia purpose
move materials along the cell surface with a brushing motion
What are cilia made up of?
microtubules
Cilia length and numbers
short
Flagella purpose
movement of the organism
What are flagella made up of?
microtubules
Flagella length and numbers
long and few
Centrioles (2)
- Short, rod-like microtubular structures
- Located near nucleus
How are centrioles used in cell divison?
Alignment and division of genetic material
