28 Questions
What is the main component of the plasma membrane?
Phospholipids with electrically charged heads and hydrophobic tails
Which organelle is responsible for regulating the intracellular environment by controlling passage of substances into and out of the cell?
Plasma membrane
How are phospholipid molecules arranged in the plasma membrane?
Like a sandwich with hydrophilic heads aligned on the outer surfaces and hydrophobic tails forming a central layer
What do membrane proteins that extend all the way through the plasma membrane provide?
Channels for passage of electrolytes and non-lipid soluble substances
What is the function of the nucleus in a cell?
Directing all metabolic activities by containing genetic material
What is the function of ribosomes in a cell?
Synthesizing proteins from amino acids
Which organelle is described as the 'power house' of the cell?
Mitochondria
What is the function of lysosomes in a cell?
Digesting foreign material and breaking down molecules inside the cell
What does DNA do in a non-dividing cell?
Directs all metabolic activities
What is the role of rough endoplasmic reticulum in a cell?
Synthesizing proteins
'The most active cell types have the greatest number of mitochondria' - Which cells are likely to have the greatest number of mitochondria?
Liver cells
'Ribosomes are also found on the outer surface of the nuclear envelope and rough endoplasmic reticulum' - What is the role of these ribosomes?
Manufacture proteins for export from the cell
What is the primary function of smooth endoplasmic reticulum?
Synthesizing lipids and steroid hormones
What is the function of the Golgi apparatus in a cell?
Packaging proteins into membrane-bound vesicles
What is contained within the nucleolus?
Components of ribosomes
What substance is found within the nucleus?
Deoxyribonucleic acid (DNA)
What is the function of facilitated diffusion in the plasma membrane?
Using specialized carrier protein molecules to transport substances
Which process involves the passive movement of water down its concentration gradient across a semipermeable membrane?
Osmosis
What is the primary role of plasma membrane in controlling entry and exit of substances?
Selectively permeable, based on size and solubility of substances
Which organelle is a central feature in all body cells, except mature erythrocytes?
Nucleus
What is the main function of active transport involving specialized protein carrier molecules?
Transporting substances up their concentration gradient using chemical energy
Which process occurs through pinocytosis and phagocytosis, involving the engulfing and digesting of particles too large to cross cell membranes?
Bulk transport
What determines which substances can pass through the plasma membrane?
Particle size and the presence of pores or channels
Which organelle is responsible for the synthesis of proteins within the cell?
Ribosomes
What is the primary role of membrane proteins in the cell?
Serving as receptors for hormones and chemical messengers
Which process involves the movement of substances across the membrane without using chemical energy?
Facilitated diffusion
Which cellular structure is responsible for producing ATP (adenosine triphosphate)?
Mitochondria
Which type of cells lack a nucleus?
Erythrocytes
Study Notes
- Membrane proteins perform various functions: acting as self markers with branched carbohydrates, serving as receptors for hormones and chemical messengers, and functioning as enzymes
- Plasma membrane is selectively permeable, controlling entry and exit of substances based on their size and solubility
- Particle size and the presence of pores or channels determine which substances can pass through the plasma membrane
- Facilitated diffusion uses specialized carrier protein molecules to transport substances across the membrane, even when they cannot diffuse through unaided
- Osmosis is a passive process of water movement down its concentration gradient towards equilibrium across a semipermeable membrane
- Active transport involves specialized protein carrier molecules using chemical energy (ATP) to transport substances up their concentration gradient
- Bulk transport occurs through pinocytosis and phagocytosis, which involve the engulfing and digesting of particles too large to cross cell membranes
- Organelles are small, membrane-enclosed structures with specialized functions in the cell, including the nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and cytoskeleton.
- The nucleus is a central organelle in all body cells, except mature erythrocytes, which lack a nucleus. Some cells, such as skeletal muscle fibers, contain multiple nuclei.
Test your knowledge of cell physiology including the structure, function, and components of the plasma membrane, rough endoplasmic reticulum, nucleus, chromatin, nucleolus, cytoplasm, and mitochondria.
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