30 Questions
What is the structure of the plasma membrane?
Consists of two layers of phospholipids with embedded proteins and sugars, along with cholesterol.
What is the function of the membranes in cell survival?
They control the passage of substances into and out of the cell, regulating the intracellular environment.
What are the components of the plasma membrane?
Phospholipids, proteins, sugars, and cholesterol.
How are phospholipid molecules arranged in the plasma membrane?
The hydrophilic heads are aligned on the outer surfaces, and the hydrophobic tails form a central water-repelling layer.
What do membrane proteins that extend through the plasma membrane provide?
Channels that allow the passage of electrolytes and non-lipid soluble substances.
What is the role of cholesterol in the plasma membrane?
It is present in the membrane structure.
What is the function of membrane proteins with branched carbohydrate molecules attached to the outside of the cell?
They give the cell its immunological identity - 'self' markers.
What is the role of the plasma membrane in regulating the cell's internal environment?
It controls the entry or exit of many substances, thereby regulating the composition of its internal environment.
How do lipid-soluble materials cross the membrane?
By dissolving in the lipid part of the membrane.
What is the process used by some substances that are unable to diffuse through the semipermeable membrane unaided?
Facilitated diffusion.
What is osmosis?
Passive movement of water down its concentration gradient towards equilibrium across a semipermeable membrane.
What drives the transport of substances across the membrane in active transport?
Chemical energy in the form of adenosine triphosphate (ATP).
What is the principal intracellular cation?
Potassium (K+).
What is the principal extracellular cation?
Sodium (Na+).
What is the process of engulfing particles too large to cross cell membranes?
Phagocytosis.
What is the function of lysosomes in phagocytosis?
Adhering to the vacuole membrane and releasing enzymes to digest the contents.
What is the reverse process of phagocytosis where waste material is extruded through the plasma membrane?
Exocytosis.
What are organelles?
Individual and highly specialised structures enclosed by their own membrane within the cytosol.
What is the largest organelle in the cell?
The nucleus
What is the genetic material present in the nucleus?
Deoxyribonucleic acid (DNA)
What is the fine network of threads called in a non-dividing cell?
Chromatin
What is the roughly spherical structure involved in the synthesis and assembly of the components of ribosomes in the nucleus?
Nucleolus
What is the function of mitochondria in the cell?
Aerobic respiration and production of ATP
What are ribosomes composed of?
RNA and protein
Where are ribosomes found when they make proteins for use within the cell?
In the cytoplasm (free units or in small clusters)
What is the function of smooth endoplasmic reticulum?
Synthesis of lipids and steroid hormones, and detoxification of some drugs
What is the site of synthesis of proteins in the cell?
Rough endoplasmic reticulum
What is the function of the Golgi apparatus?
Packaging proteins into membrane-bound vesicles
What do lysosomes contain?
Enzymes involved in breaking down fragments of organelles and large molecules
What is the function of lysosomes in white blood cells?
Digesting foreign material such as microbes
Test your understanding of cell physiology with a focus on the plasma membrane and organelles. This quiz covers topics such as rough endoplasmic reticulum, nuclear envelope, nucleus, chromatin, nucleolus, cytoplasm, and mitochondria.
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