2A - Cell Structure And Division Flashcards
What are eukaryotic and prokaryotic cells?
• Eukaryotic
- are complex
- animal, plant, fungi organisms consist of them.
- have membrane bound organelles
• prokaryotic
- are smaller and simpler
- bacteria, eg, are prokaryotic cells (are single-celled)
- No membrane bound organelles
What’s a cell-surface/plasma membrane
Membrane found on surface of animal cells; inside cell walls of other cell types.
Made up of lipids and protein.
- regulates movement of substances in/out cell
- has receptor molecules on it, to respond to chemicals like hormones
- has antigens that system sees as safe
What’s the description and function the nucleus and its parts?
It’s a large organelle surrounded by nuclear envelope (double membrane).
They have many nuclear pores.
It’s filled by the nucleoplasm
Contains chromatin wch condenses into chromosomes (made from protein bound linear DNA)
Has a nucleolus
- nucleus controls cell activities by controlling DNA transcription.
- DNA contains instructions to make proteins.
- pores allow substances (mRNA eg) to move in/out nucleus
- Nucleolus makes ribosomes (synthesises ribosomal RNA + assembles)
Mitochondrion description and function , including parts
They’re usually oval shaped with a double membrane.
The inner membrane is creased to create folds called christae
Christae increase SA so respiration = faster
Inside inner membrane is matrix (contains enzymes for respiration)
- mitochondria are site of respiration where ATP is produced
- ATP are energy carrier molecules
- The more active the cell, the more mitochondria (more energy needed)
What’s Golgi apparatus? And vesicles?
A group of membrane-bound flattened sacs (cisternae)
Vesicles (little dots) are often at edges of sacs, produced by Golgi apparatus
Vesicles are small fluid-filled sacs in cytoplasm surrounded by a membrane
- they modify and package new lipids and proteins/enzymes
- the vesicles transport and store them.
- also makes lysosomes.
What’s a lysosome
a round organelle surrounded by a membrane - no clear internal structure
It’s a type of golgi vesicle
- contains lysozymes (digestive enzymes)
- kept separate from cytoplasm by its membrane
- uses lysozymes to digest invading cells, or to break down worn cell components.
What are the extra organelles in plant cells
They have same organelles as animal cells but with
- a cellulose cell wall (with plasmodesmata; channels to exchange substances with adjacent cells)
- a vacuole
- chloroplasts
What are the structures of algae and fungal cells
• Algae
- have all same organelles as plant cells
- they carry out photosynthesis, but can be single-celled or multicellular
• Fungal cells (mushrooms, yeast)
- like plant cells with differences.
- cell walls of chitin not cellulose
- no chloroplasts (don’t photosynthesise)
What’s structure and function of chloroplasts
Small flattened structure..
- surrounded by double membrane
- also has membranes inside (thylakoid membranes)
- these membranes stack up in some parts of the chloroplast (grana)
- grana are linked by lamellae (thin flat thylakoid membrane pieces)
The site of photosynthesis
Initial parts of photosynthesis happen in the grana
Then in the stroma (thick fluid in chloroplasts)
Ribosome described and function
A very small organelle (floats free or attached to RER)
- made up of proteins and RNA
- no membrane
Site of protein synthesis
Rough endoplasmic recticulum structure and function
System of membranes enclosing on fluid-filled space.
Surface covered in ribosomes
Function
- folds and processes (sort and modified) proteins made at ribosomes
Smooth endoplasmic recticulum structure and function
Same as rough endoplasmic recticulum (no ribosomes)
—> more tube-like
Synthesises and processes lipids, as function.
Stores and transports lipids too.
What are structure and functions of cell wall and vacuole?
•Cell wall
- rigid structure, surrounds plant, algae and fungi cells
- cellulose in plants and algae
- chitin in fungi
As a function, it supports cells, preventing change in shape.
• vacuole
- membrane bound organelle on ONLY plant cell cytoplasm
- cell sap inside (weak sugar and salt solution)
- membrane is called the tonoplast
Function..
Is to maintain pressure in cell to keep it rigid
Stopping plants wilting.
Also involved in isolating unwanted chemicals in cell.
What’s the structure of prokaryotic cells, and its organelle functions
They’re smaller and simpler than eukaryotic cells (DIAGRAM NO. 2)
•cell wall
Supports cell preventing shape change
Made of murein, a polymer.
—> It is a glycoprotein (protein with carb attached).
• plasma membrane
Made of lipids and proteins
Controls what exits and enters cell
• cytoplasm
Has no membrane bound organelles
Has smaller ribosomes than those in eukaryotic cells
• flagellum
Long hairlike structure that rotates to make cell move
(Not all have it. Some have more than one)
• no nucleus
- DNA floats free in cytoplasm
It’s circular, a coiled up strand
Not attached to histone proteins
- plasmids are small dna loops
Not part of main circular DNA molecule
Contains genes for antibiotic resistance AND can be passed between prokaryotes
(Not always present; some have several)
• capsule
Made up of secreted slime
To protect bacteria from attack by cells in immune system
Also helps groups of bacteria stick together
What is cell fractionation
It’s the process of separating organelles.
Cell fractionation makes it possible to view organelles under an electron microscope.
There are 3 steps….
- homogenisation
- filtration
- ultracentrifugation
What’s homogenisation
It’s breaking up the cells
• it can be done in many ways,
like grinding cells in a blender
Or vibrating the cells.
—> this breaks up plasma membrane and releases organelles into solution
—> Conditions..
- kept ice-cold
To reduce enzyme activity that break down organelles. - solution shd be isotonic
Having same conc of chemicals/solute/water pot. As inside cells
To prevent organelle damage by osmosis - maintain pH
By adding buffer solution
