Lecture 1 - Cell Structure & Function Flashcards
What is the difference between cells, tissues, organs and systems?
Cells make up all living organisms.
Groups of specialized cells group to form different tissues.
Groups of different tissues work together to perform a function in an organ.
A collection of tissues/organs may form a system.
What are the main components of human cells?
A cell membrane
Nucleus - directs cellular activities, stores DNA
Organelles (SER, RER, Golgi Apparatus etc)
Cytosol - surrounds organelles
Cytoplasm - incl cytosol and all organelles
Extra-cellular matrix - surrounds cell and holds it together
What are the basic functions of human cells?
Cellular Metabolism - breaking down to yield energy, or expending energy
Communication - using chemical and electrical signals
Reproduction & Inheritance - through DNA
What is homeostasis? How is this relevant to human cells?
Homeostasis is the steady state functioning of the cell, where a relatively constant environment is maintained within the body, and within cells.
Cells only function correctly in a tightly regulated environment, so if homeostasis is not achieved, death will quickly occur.
What is the basic structure and function of the cell membrane?
It is a semi-permeable barrier that protects the cell from the external environment, regulates cellular transport and transmits signals.
Made up of lipids, proteins and carbohydrates.
Regulates the movement of substances in and out of cells which helps to maintain cell homeostasis.
What is passive transport? Name an example.
Water/Small uncharged molecules move from regions of high concentration to low concentration, without the requirement for energy. E.g:
Diffusion - move directly through, down concentration gradient (high to low conc.)
Osmosis - diffusion of water molecules from region of higher water concentration to lower (diluted solution contains a HIGH concentration of water molecules)
Facilitated Diffusion - faster than simple diffusion as they use channel proteins or carrier proteins.
What is active transport? Name an example.
Larger or electrically charged molecules are moved through the cell membrane using energy, and often bound by receptors E.g.
Primary Active - utilises energy derived from ATP, moves against conc. gradient (Na+ K+ pump - 3Na+ exit the cell and 2K+ enter)
Secondary Active - uses ionic concentration differences and a channel or carrier protein.
Vesicular - Endocytosis (take into cell - pinocytosis brings liquid, phagocytosis brings larger/solid molecules) and Exocytosis (exits the cell).
How are chemical concentration gradients and electro-chemical gradients relevant to cell transport?
To move substances against a concentration or electro-chemical gradient, a cell must use energy to transport. The cell has a resting potential, which is maintained by Na+/K+ pumps in the cell membrane.
