Cell Structures and Functions (Mader Chapter 3) Flashcards
What is the basis of cell theory?
That all living things are made of cells
Cells are the units of all living things
Cells differentiate into different types with different functions.
Which tissues are cells organized into
Connective
Epithelial
Muscle
Nervous
Why are cells small?
Because of their surface-area-to-volume ratio
Talk about surface area, why is it important?
Smaller cells have a larger surface area compared to the volume.
An increase in surface area allows for more nutrients to pass into the cell and more wastes to exit the cell.
There is a limit to how large a cell can be while remaining efficient and metabolically active.
What are the structural characteristics of the plasma (cell) membrane?
Phospholipid bilayer , hydrophilic head face the cytoplasm and extracellular fluid
Contains cholesterol for support
Glycoproteins and glycolipids
(carb. chains attached to proteins and lipids)
- identify the cell as “self” or foreign and act as receptors
Whats the difference in cell membranes amongst cells?
They differ in composition of lipids, proteins, and carbohydrates.
Ex: the inner mitochondrial membrane is full of transport proteins
How do substances get across the cell membrane?
Diffusion Osmosis (H20) Facilitated diffusion Active transport Endocytosis/ Exocytosis
Explain diffusion
The random movement of molecules from a net movement of
HIGH CONCENTRATION to LOW CONCENTRATION
- PASSIVE movement
Types of molecules that diffuse:
Gases
Water molecules
Lipids (steroid hormones)
Explain Osmosis
The diffusion of water from a
HIGH CONCENTRATION to a LOW WATER CONCENTRATION
Hypotonic : solutions have fewer solutes
Hypertonic: Solutions have more solutes
Isotonic: Cells have the same concentration of impermeable solutes .
Osmotic pressure - drives osmosis
Explain Facilitated Transport.
Transport of molecules across the plasma membrane from
HIGH CONCENTRATION to LOW CONCENTRATION
Passive transport
use protein transporters
Explain Active transport
The movement of molecules from
LOWER CONCENTRATION to HIGHER CONCENTRATION (Against the gradient)
ATP is used as energy
Requires a specific protein carrier known as a “pump”
Explain the Sodium-Potassium pump (Na+ & K+)
Na+ is higher outside the cell and K+ is higher inside so the the pump functions to move NA+ out and K+ in. (helps maintain ion gradients)
What are the bulk transport modes to move large molecules across the membrane.
Endocytosis:
Phagocytosis
Pinocytosis
Receptor-mediated endocytosis
What is Endocytosis?
Transports molecules or cells into the cell via invagination of the plasma membrane to form a vesicle.
What is Phagocytosis?
Endocytosis of pathogens by white blood cells (engulf).
What is Pinocytosis?
Endocytosis of fluid with small particles
What is Exocytosis?
transports molecules outside the cell via the fusion of a vesicle with the plasma membrane.
What are some characteristics of the nucleus?
It is a double membrane structure. Contains chromatin (a complex of DNA that condenses into discrete chromosomes during cell division, histones and other proteins)
What is the nucleolus?
A dense area within the nucleus which directs the synthesis and processing of ribosomal RNA (rRNA: controls gene expression.)
What is the function of the nucleus?
Store genetic information.
What is the difference between free and membrane bound ribosomes?
Free ribosomes are free in the cytoplasmic matrix and membrane bound are attached to ER.
What are the components of the Endomembrane system?
Nuclear envelope Endoplasmic Recticulum (RER vs SER) Golgi apparatus Lysosomes Vesicles
What is the function of the Endoplasmic Reticulum?
The enzymes associated with the ER are involve in synthesis of proteins for
- Incorporation into the plasma membrane
- Organelles of the end-membrane system
- Export from the cell
Also involved in lipid synthesis.
What is the difference between the RER and SER?
Rough ER - characterized by the ribosomes on the cytosolic side of the membrane + Large Flattened sheets
Cells involve in synthesis of secretory proteins have mainly RER
Smooth ER- lacks ribosomes + tubular structures
Cells producing steroid hormones have an extensive network of SER
