CTL Flashcards
Describe homeostasis
Homeostasis is the stable internal environment in which the constituents of the body (i.e. cells, proteins, enzymes, etc.) function. This is maintained despite the ever-changing external world.
What is the Principle of Complementarity of Structure?
The principle states that anatomical structure is intrinsically linked with physiological function; structure and function are dependent off each other
Outline the organisation of the body
Molecules -> Cells -> Tissues -> Organs -> Systems -> Body
Outline Cell Theory
- Cells are the most basic functional units of life
- Cells are alive and dynamically changing
- Cell structure and function are intrinsically linked
- Cells have a ‘life cycle’ known as the cell cycle
What are the stages of the cell cycle?
Cell is predominantly in Interphase but will go into mitotic phases when replicating
Outline Interphase
- G1: the cell grows and is metabolically active
- S: DNA begins to replicate (synthesis stage)
- G2: Cell finishes growing; enzymes and other proteins are synthesised; DNA replication is completed
What is the first phase of Mitosis and what occurs?
Prophase: DNA (chromatin) condenses into chromosomes and the mitotic spindle begins to form (nucleus disappears)
What is the second phase of Mitosis and what occurs?
Metaphase: Chromosomes are lined on the metaphase plate of cell by microtubules (centromeres are in the exact centre)
What is the third phase of Mitosis and what occurs?
Anaphase: Spindle fibres shorten, causing chromosomes to separate at centromeres. The sister chromatids then move to opposite poles of the cell
What is the fourth phase of Mitosis and what occurs?
Telophase: Following chromatid movement, a nucleus reappears around the chromatids. The chromatids uncoil into chromatin
What is the final phase of Mitosis and what occurs?
Cytokinesis: The cell is cleaved into two identical daughter cells
What type of cell is Bacteria?
Prokaryote cell (no nucleus)
What type of cells do humans have?
Eukaryote cells (membrane-bound nucleus)
Compare and contrast prokaryote and eukaryotes (size; cell wall; nucleus; genetic material; membrane-bound organelles; plasma membrane; endoplasmic reticulum; ribosomes and reproduction)
- Size: prokaryotes significantly smaller than eukaryotes
- Cell wall: always present in prokaryotes, sometimes present in eukaryotes
- Nucleus: prokaryotes have no defined nucleus, eukaryotes do
- Genetic material: prokaryotes have one circular chromosome, eukaryotes have multiple
- Membrane-bound organelles: only present in eukaryotes
- Plasma membrane: present in both types
- Endoplasmic Reticulum: only present in eukaryotes
- Ribosomes: smaller in prokaryotes (70s), larger in eukaryotes (80s)
- Reproduction: prokaryotes are largely asexual, eukaryotes are asexual and sexual
How does a Gram-positive Bacteria differ from a Gram-negative Bacteria?
- Gram positive bacteria have a thick outer layer of peptidoglycan (PG)
- Gram negative bacteria have a PG layer sandwiched between two membranes
What colour are Gram Postive and Gram Negative Bacteria?
- Gram Positive: blue/purple
- Gram Negative: red/pink
What is a key feature of antibiotic drugs?
Selective toxicity, they only kill target organisms and not host cells
What are the four main target sites for antibiotics?
- Inhibition of cell wall synthesis
- Inhibition of protein synthesis
- Inhibition of nucleic acid synthesis
- Disruption of cell membrane function
What is a bactericidal drug and how does it differ from a bacteriostatic?
Bactericidals kill bacteria, whereas bacteriostatics only slow growth/replication
Outline the three main structural features found in most cells
- Cell membrane: forms a barrier and allows cells to be self-contained
- Nucleus: the control centre of the cell responsible for cell activity
- Cytoplasm: intracellular solution that houses all organelles and structures required for function
Where would you find integral and peripheral proteins? What are their functions?
On plasma membrane.
Integral proteins are a functional part of the cell membrane– drive cell activity. Peripheral proteins include receptors that stimulate intracellular activity
What are some functions of the cell membrane?
Transport; providing receptors for signal transduction; controlling cytoskeleton; enzymatic activity; intracellular joining and cell-cell recognition
How are cells joined? Briefly describe.
Cell junctions.
Tight Junctions: binding connection where extracellular fluid space is eliminated to prevent substances from passing in between cells
Desmosomes: anchored junction (bound by plaques and collagen)
Gap Junctions: a functional connection allowing the movement of molecules between cells
What are the two different transport mechanisms used by cells? How do they differ?
Passive and active transport. Passive transport relies on materials moving along concentration gradients; active transport utilises energy to move things against concentration gradients
What is the function of the mitochondria?
The mitochondria is the organelle responsible for energy production in a cell
What is the function of the Endoplasmic Reticulum (ER)
Rough ER has ribosomes which synthesis proteins; Smooth ER synthesises lipids and carbohydrates
What is the function of the Golgi Apparatus
The Golgi Apparatus modifies, packages and transports various proteins from the Rough ER. It receives proteins from its cis-face and transports via the trans-face
What does a lysosome do?
Lysosomes are responsible for breaking down and digesting various toxins or old/damaged parts of the cell
How does the cell move?
The cell moves thanks to the cytoskeleton (cell skeleton) and the centrosomes, which contain centrioles (microtubules)
Cilia and microvilli are examples of what?
They are cellular extensions, which are projections of the cell membrane
What are the four different cell types in the body?
Epithelia; connective; muscle and nervous
What are epithelial cells?
Cells that line the external and internal surfaces of the body. They also form boundaries and coverings of various body structures.