The Cell Flashcards
What is a cell?
- The smallest unit of life
- It’s characteristics include: responsiveness, respiration, digestion, growth, absorption, assimilation, circulation, excretion, movement, and reproduction.
What are the 3 major parts of a cell?
Cell membrane, Nucleus and Cytoplasm
What is the function of the cell membrane?
Protects the structural integrity of the cell, regulates the entry and exit of substances, communicates and interacts with other cells, and transports messages into other cell.
Helps cells attach to certain other cells, helping form tissues.
What is the function of the nucleus?
Stores DNA, Directs the cell’s activities, and produces Ribosomes
What is the function of the cytoplasm?
The cytoplasm consists of fluid and organelles. These organelles perform basic cell functions like…
- Food breakdown to produce energy and heat
- Protein and lipid production and packaging
- Maintains cell shape
What is the (chemical) structure of the cell membrane?
Thin, flexible and composed mainly of lipids and proteins and some carbohydrates.
Has a bilayer of phospholipid molecules, which are made up of a phosphate group and fatty acids bound to a glycerole molecule.
Is Semi permeable, meaning it only allows certain molecules to pass through easily.
The phospholipid molecules have water-soluble heads that face the surfaces of the membrane and their lipid-soluble tails face the membrane interior.
What molecules can easily pass through the phospholipid bilayer of the cell membrane?
Oxygen and CO2
What molecules cannot pass easily through the phospholipid bilayer of the cell membrane?
Water-solube molecules such as,
amino acids, sugar, proteins, nucleic acids, and certain ions.
What molecule, embedded in the cell membrane, makes it impermeable to certain molecules?
Cholesterol Molecules
What types of proteins are found in the structure of the cell membrane?
Integral Proteins: Extend through the lipid bilayer and may portrude from one or both faces.
Proteins also vary in shape - globular, rodlike or fibrous.
What is the function/s carried out by proteins within the cell membrane structure?
- Some form receptors on the cell surface that bind incoming hormones or growth factors, starting signal transduction.
- Others transport ions or molecules across the cell membrane.
- They can form ion channels in the phospholipid bilayer that allow only particular ions to enter or leave the cell.
What is the structure of ribosomes?
- Tiny, spherical structures that are composed of protein and RNA.
- Scattered in the cytoplasm and also bound to the endoplasmic reticulum.
What is the function of ribosomes?
- They provide structural support and enzymatic activity to link amino acids to synthesize proteins.
What is the endoplasmic reticulum (includes function)?
A complex organelle composed of membrane-bound, flattened sacs, cylinders and fluid-filled, bubble-like sacs called vesicles.
It participates in the synthesis of protein and lipid molecules.
What are vesicles?
Membranous sacs that store or transport substances within a cell and between cells. Larger vesicles that contain mostly water form when part of the cell membrane folds inwards and pinches off, bringing solid material from outside the cell into the cytoplasm.
