Chapter 2 Flashcards
What are the two major parts of cells?
The nucleus and cytoplasm
How is the nucleus separated from the cytoplasm?
By a nuclear membrane
What is the protoplasm?
The different substances that make up the cell. Composed of mainly five substances
Which cells are not mainly comprised of water?
Fat cells
In what concentration are most cells comprised of water?
70-85%
What are important ions in cells?
Potassium, magnesium, phosphate, sulfate, bicarbonate and smaller quantities of sodium, chloride and calcium.
After water, what is the most abundant substance in most cells?
Proteins
How much do protein constitute of the cell mass?
10-20%
In what two types can proteins be divided?
Structural proteins and functional proteins
What is the common property of lipids?
They are soluble in fat solvents
What are two important lipids?
Phospholipids and cholesterol
How much of the body mass do phospholipids and cholesterol constitute?
2% of the body mass
What is another name for triglycerides?
Neutral fats
What are adipocytes?
Fat cells
How much of the cell mass do triglycerides constitute in cells?
95%
What is glycogen?
Stored carbohydrate in the cell, it is an insoluble polymer of glucose
How much of the cell’s energy release from nutrients would cease immediately without the presence of mitochondria?
95%
What is the function of lipids in membranes?
Provide a barrier that impedes movement of water and water-soluble substances from one cell compartment to another
How thick is the cell membrane (plasma membrane)?
7.5 - 10 nanometers
What is the composition of the cell membrane?
55% proteins, 25% phospholipids, 13% cholesterol, 4% other lipids and 3% carbohydrates
Of which 3 main types of lipids is a basic lipid bilayer composed?
Phospholipids, sphingolipids and cholesterol
Which end of a phospholipid is hydrophilic (water soluble)?
Phosphate end
Which end of a phospholipid is hydrophobic (fat soluble)?
Fatty acid portion
What are water soluble substances?
Ions, glucose and urea
What are fat soluble substances?
Oxygen, carbon dioxide and alcohol
Where are sphingolipids derived from?
The amino alcohol sphingosine
What are the three functions of complex sphingolipids?
1) protection from harmful environmental factors
2) signal transmission
3) adhesion sites for extracellular proteins
What is the main function of cholesterol molecules in the membrane?
They help determine the degree of permeability of the bilayer to water-soluble constituents of body fluids.
What are two types of cell membrane proteins?
Integral proteins and peripheral proteins
What is the main function of integral proteins?
Provide a means of conveying information about the environment to the cell interior.
In what do peripheral proteins play a role?
Support, communication, enzymes and molecule transfer in the cell.
What are proteoglycans?
Mainly carbohydrates bound to small protein cores.
What is the Glycocalyx?
A loose carbohydrate coat around the entire surface of the cell.
What is dispersed in the cytoplasm?
Neutral fat globules, glycogen granules, ribosomes, secretory vesicles and five important organelles.
What are the five organelles present in the cytoplasm?
Endoplasmic reticulum, golgi apparatus, mitochondria, lysosomes and peroxisomes.
What is mainly dissolved in the cytosol?
Proteins, electrolytes and glucose
What are cisternae?
A network of tubular structures in the endoplasmic reticulum.
Of what does the endoplasmic reticulum consist?
Cisternae + flat vesicular structures
What is the function of the endoplasmic reticulum?
Help process molecules made by the cell and transport them to their specific destination inside or outside the cell.
What are ribosomes?
Minute granular particles, composed of a mixture of RNA and proteins.
What do ribosomes do?
They synthesize new protein molecules in the cell.
In what cells is the Golgi apparatus prominent?
Secretory cells
Of what is the Golgi apparatus usually composed?
Four or more stacked layers of thin, flat, enclosed vesicles lying near one side of the nucleus.
Transported substances are processed in the Golgi apparatus to form….
Lysosomes, secretory vesicles and other cytoplasmic components.
What is the function of lysosomes?
They provide an intracellular digestive system that allows the cells to digest substances.
What can be digested by the lysosomes?
Damaged cellular structures, food particles that have been ingested by the cell and unwanted matter (bacteria f.e.)
What is usually the diameter of lysosomes?
250-750 nanometers
What are small granules?
Protein aggregates of 40 different hydrolase (digestive) enzymes. They are found inside lysosomes.
What is the diameter of small granules?
5-8 nanometers
What is the function of hydrolytic enzymes (found in lysosomes)?
They hydrolyze an organic compound into two or more parts.
How is a peroxisome different from a lysosome?
They are believed to be formed by self-replication and they contain oxidases instead of hydrolases.
What are protein proenzymes?
Enzymes that are not activated yet.
What are the mitochondria?
The powerhouses of the cell
Where are mitochondria present?
In all areas of the cell’s cytoplasm
What are cristae (in mitochondria)?
Infoldings of the inner membrane
What is the function of the cristae (in mitochondria)?
They provide a large surface area for chemical reactions to occur.
What is the ectoplasm?
The outer zone of the cytoplasm
What is the diameter of a microfilament?
7 nm
What is the diameter of an intermediate filament?
8-12 nm
What is the diameter of a microtubule?
25 nm
Where are desmin filaments found?
In muscle cells
Where are neurofilaments found?
In neurons
Where are keratins found?
In epithelial cells
What are the 4 functions of the cell cytoskeleton?
1) Determining cell shape
2) Participating in cell division
3) Allowing cells to move
4) Providing a track like system that directs movement of organelles in the cells
Where are genes found?
Inside DNA
What is the function of genes?
They determine the characteristics of the cell’s proteins.
How large is the central area of pores in the nuclear membrane in diameter?
9 nanometers
Molecules with what molecular weight can pass through the pores of the nuclear membrane with reasonable ease?
40,000 g/mol
Uit wat bestaat de nucleolus (celkern)?
Het is een ophoping van grote hoeveelheden RNA and eiwitten die nodig zijn voor het vormen van ribosomen.
How much larger is the diameter of a cell compared to the smallest virus?
1000 times
How much larger is the volume of a cell compared to the volume of the smallest virus?
1 billion times
What is a small protein?
A nucleic acid embedded in a coat of protein
What is the size of a small virus?
15 nm
What is the size of a large virus?
150 nm
What is the size of a Rickettsia?
350 nm
What is the size of a bacterium?
1 micrometers
What is the size of a cell?
5-10 micrometers
What is the most important organelle in a cel?
Nucleus
What are two principal forms of endocytosis?
Pinocytosis and phagocytosis
What are examples of large particles ingested by phagocytosis?
Bacteria, whole cells or portions of degenerating tissue
How large is the diameter of pinocytotic vesicles?
100-200 nanometers
What is clathrin?
Latticework of fibrillar protein located on the inside of the cell membrane.
What cells are capable of phagocytosis?
Tissue macrophages and some white blood cells
What are the products of digestion of a digestive vesicle?
Small molecules of substances such as amino acids, glucose and phosphates.
