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
What are the functions of the Golgi apparatus?
To transport and modify proteins
What are the functions of Lysosomes?
Fuse with endosomes (vesicles) and Contain hydrolytic enzymes that break down macromolecules
What are Peroxisomes and what do they do?
Are bound to single membranes but are not derived from the ER
Detoxify harmful compounds , oxidize long fatty acids, metabolize nitrogen containing compounds , catabolism of unusual substances such as short-chain alkanes.
What are the compomenets of the Cytoskeleton?
Microfilaments
Microtubules
Intermediate filaments
What are the fucntions of Microtubules
made of tubulin
maintain cell shape and Acts as tracks along which organelles move
Form the spindle apparatus which helps move chromosomes
assembled under the control of
centrosome
Largest component
What are the functions of the Microfilaments?
Made of actin
Produce movement of cell edges as pseudopodia
Move contents of cell interior
What are the functions of Intermediate filaments?
Produce structure not movements
Helps cells maintain shape
Form network of nuclear lamina
What is the role of Cilia and Flagella?
Produce movement using ATP to power movement of dyne motor proteins along microtubules.
Flagella are long (sperm tails)
Cilia are shorter and arranged in rows (respiratory epithelium & Fallopian tube epithelium)
What are the structures of cell junctions?
Tight junctions
Adhesion junctions
Gap junctions
What are the functions of tight junctions?
Fuses membranes between cells to make a barrier and prevent leakage between cells
What are the functions of adhesion (desmosomes?)
Provide strength at stress points
Adjacent cells connected to cytoskeleton with intermediate filaments
Ex: Cardiac muscle and skin
What are the functions of gap junctions?
Channels connect cells
Allow direct flow of ions
Important in muscle
What is the role of the Mitochondria?
To make ATP
More abundant in tissues that use more energy (muscles and nerves)
Also involved in synthesis, modification , and breakdown of several types of cellular molecules
What are the components of the extracellular matrix?
Collage,
Elastin
Fibronectin
Integrin
What is the function of collagen?
Provides strength and resists stretching
What is the function of Elastin?
Provides resilience
What is the function of Fibronectin?
Adhesive protein that connects ECM to integral.
What is the function of Integrin?
Family of integral membrane proteins
- Connect to cytoskeleton
- Participate in cell signaling
What is the purpose of the outer membrane and inner membrane folded with cristae in the mitochondria?
Outer membrane forms shape
Inner membrane increased surface area
Whats unique about mitochondrial replication?
It has its own dna AND ribosomes
What the overall take away from glycolysis ? (occurs in mitochondria)
1 glucose molecules breaks down into 2 pyruvate
Net gain:
2 ATP
2 NADH
What happens when the Pyruvate moves into the mtochondria?
it’s broken down
1 NADH for each pyruvate
A molecule of CO2 is removed from each pyruvate
What happens when the Pyruvate moves into the mtochondria?
it’s broken down
1 NADH for each pyruvate
A molecule of CO2 is removed from each pyruvate , remaining acetal group is attached to CoA to make acetyl CoA
Whats the take away from the Krebs cycle?
Takes place in the mitochondrial matrix
Acetyl is removed from Acetyl CoA and attached to oxoloacetate to form citric acid
Relases 2 CO2, 1 ATP, 3 NADH and 1 FADH in the process.
What is the take away from the Electron Transport Chain?
movement of electrons generate a H+ GRADIENT (proton motive force)
This provides energy for the next step - synthesizing ATP
Makes yo ti 30 to 34 ATP molecules/ glucose
Why does fermentation happen?
Cells use fermentation when oxygen isn’t available.
Only glycolysis is used
IN MUSCLE CELLS:
Reduce pyruvate to lactate (lactic acid) This takes electrons from NADH creating NAD+
Yields 2 ATP
In Anaerobic conditons:
NADH can build up, causing problems
The cytoplasm of a eukaryotic cell is crisscrossed by several types of supportive protein fibers, which are collectively called the ___
extracellular matrix
