The Microscopic Structure of cells Flashcards
What four features do all cells share?
Plasma membrane, Cytosol, Chromosomes, Ribosomes
How large are prokaryotes and eukaryotes and which are larger?
prokaryotes (1-10um) and eukaryotes (10-100um). Prokaryotes require a microscope, eukaryote cells are larger
What are two defining features of prokaryotic cells
No nucleus (nucleoid contains DNA) and no membrane-bound organelles
What three shapes can prokaryotic cells be
Cocci (Spherical) bacilli (rod), spirilli (Helical)
What are the two defining features of eukaryotic cells
Contain a true nucleus and have membrane bound organelles
What is the nucleus, what is it enclosed by, why is it porous?
Contains most of DNA, enclosed by nuclear envelope (double membrane), pores allow regulation of compounds to move in and out of nucleus
What are ribosomes and where are they located
Ribosomes are responsible for protein synthesis using instructions from DNA. Some are free within the cytosol, some are membrane bound to the endoplasmic Reticulum or nuclear envelope
What is the Endoplasmic reticulum and what is its purpose
Network of membranal tubes and sacs called cisternae, it separates the internal compartment of ER from cytosol
What is the purpose of rough ER
Responsible for the synthesis of secretary proteins
- hormones and enzymes
- creates membrane proteins and lipids
Name the 4 purposes of smooth ER
- Responsible for synthesising lipids
- Metabolising carbohydrates
- Detoxification of the cell
- Stores calcium ions
What is the physical difference between smooth ER and rough ER
Rough ER contains ribosomes on the surface, whereas smooth does not
What is the Golgi Apparatus and what are its two functions
Acts as the transport warehouse of the products produced from the ER.
- Usually modifies proteins (through adding or subtracting sugar monomers) before sending them out to the cell
- Produces polysaccharides
Where do vesicles form and what are their functions
- They form in the golgi apparatus
- Transport products around the cell or to the plasma membrane for secretion
What are lysosomes
- The digestive compartments of a eukaryotic cell
- A sac of hydrolytic enzymes used to digest macromolecules into smaller parts // breaks down substances into smaller molecules so that they can be used by the cell
What two processes are Lysosomes involved in
- Phagocytosis = Digestion of external molecules (where one cell engulfs another cell or particle)
- Autophagy = The way their body cleans out the damaged cells (intracellular components are recyled)
What is a vacuole and what three types of vacuoles are there
A vacuole is a space empty of cytoplasm, lined with membrane, filled with fluid
Three types:
1. Food vacuole (formed by phagocytosis)
2. Contractile Vacuoles (excess water is secreted out of cell to maintain ion conc.)
3. Central vacuole (in plant, contains cell sap, major role in plant growth and storage)
What are the mitochondria, how many per cell, are they mobile, how large are they?
- convert chemicals into energy to help us perform work and is where cellular respiration occurs
- POWERHOUSE OF THE CELL
- it performs/provides energy for the cell
- can range from one to hundreds or thousands depending on type of cell
- Yes, they are mobile
- Size ranges from 1-10 micrometres
What three things is the cytoskeleton comprised of and what is its function
- Microfilaments, Intermediate filaments, Microtubules
- Fibres extend throughout cytoplasm and provide mechanical support
- motility for cells
What is the main difference in function between animal and plant cells
How they get their energy
plants
-chloroplasts convert light energy to chemical energy through a process known as photosynthesis
- can be found in leaves, algae, green parts of plants
- are mobile
- small (3-6 micrometres)
animal
What are four similarities and two differences between plant and animal cells
Similarities = membrane, nucleus, cytosol, mitochondria
differences = only plant cells have chloroplasts, different shapes for cell wall
Why is a plant cell wall shape rigid
provides support and allows plants to grow tall with no skeleton
