Lecture 1 Flashcards
What characteristics are shared by living organisms?
- Organised from the atom to the biosphere
- Use materials and energy from the environment
- Reproduce offspring
- Growth and development
- Maintain a relatively constant internal environment (homeostasis)
- Respond to internal and external stimuli
- Evolutionary history through which organisms change over time
How are living things organised? (Atom to Biosphere)
Atom Molecule Cell Tissue Organ Organ system Organism Population Community Ecosystem Biosphere
How do we classify humans?
Domain - Eukarya Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Primates Family - Hominidae Genus - Homo Species - Sapiens
What distinguishes humans?
- Cultural heritage or patterns of our behaviour passed from one generation to the next
- Highly developed brains
- Completely upright stance
- Creative language skills
- Varied tool use
- Modification of our environment for our own purpose which may threaten the biosphere
Concept of Cells
All organisms are composed of cells, and new cells only come from pre-existing cells.
Concept of Homeostasis
The internal environment of an organism stays relatively constant
Concept of Genes
Organisms contain coded information that dictates their form, function and behaviour
Concept of Ecosystem
Populations of organisms interact with each other and the physical environment
Concept of Evolution
All organisms have a common ancestor, but each is adapted to a particular way of life
Why are most cells small?
- Small cells have a larger amount of surface area compared to volume
- An increase in surface area allows for more nutrients to pass into the cell and wastes to exit the cell more efficiently
- There is a limit to how large a cell can be and be an efficient and metabolically active cell
What are common microscopes used to view cells?
- Compound light microscope
- Lower magnification
- Uses light beams to view images
- Can view live specimens - Transmission electron microscope
- 2-D image
- Uses electrons to view internal structure
- High magnification, no live specimens - Scanning electron microscope
- 3-D image
- Uses electrons to view surface specimens
- High magnification, no live specimens
What are the 2 major types of cells in all living organisms?
Prokaryotic cells
- Thought to be the first cells to evolve
- Does not have a nucleus
- Represented by bacteria and archaea
Eukaryotic cells
- Have a nucleus that houses DNA
- Many membrane-bound organelles
What do prokaryotic and eukaryotic cells have in common?
- A plasma membrane that surrounds and delineates the cell
- A cytoplasm that is the semi-fluid portion inside the cell that contains organelles
- DNA
Where did eukaryotic cells come from?
- Cells gains a nucleus by the plasma membrane invaginating and surrounding the DNA with a double membrane.
- Cells gain an endomembrane system by proliferation of membrane.
- Cells gain protomitochondria.
- Cell gains protochloroplasts.
What are the characteristics of the plasma membrane?
- It is a phospholipid bilayer
- It is embedded with proteins that move in space
- It contains cholesterol for support
- It contains carbohydrates on proteins and lipids
- Selectively permeable
What does selectively permeable mean?
The membrane allows some things in while keeping other substances out.
How do things move across the plasma membrane?
- Diffusion
- Osmosis
- Facilitated transport
- Active transport
- Endocytosis and exocytosis
What is diffusion and what is osmosis?
- Diffusion is the random movement of molecules from a higher concentration to a lower concentration.
- Osmosis is the diffusion of water molecules
How does tonicity change a cell?
- Hypertonic solutions have more solute than the inside of the cell and lead to lysis (bursting)
- Hypotonic solutions have less solute than the inside of the cell and lead to crenation (shrivelling)
- Isotonic solutions have equal amounts of solute inside and outside the cell and thus does not affect the cell.
What are facilitated diffusion and active transport?
Facilitated transport is the transport of molecules across the plasma membrane from higher concentration to lower concentration via a protein carrier.
Active transport is the movement of molecules from a lower to higher concentration using ATP as energy; requires a protein carrier.
What are endocytosis and exocytosis?
- Endocytosis transports molecules or cells into the cell via invagination of the plasma membrane to form a vesicle.
- Exocytosis transports molecules outside the cell via fusion of a vesicle with the plasma membrane.
What structures are involved in protein production?
- Nucleus
- Ribosomes
- Endomembrane System
What is the structure and function of the nucleus?
- Bound by a porous nuclear envelope
- Houses DNA and associated proteins called chromatin
- Contains nucleoplasm
Nucleolus region(s) that contain ribosomal RNA (rRNA)
What is the structure and function of ribosomes?
- Organelles made of RNA and protein
- Found bound to the endoplasmic reticulum and free floating in the cell
- Site of protein synthesis
What is the endomembrane system?
- A series of membranes in which molecules are transported in the cell
- It consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes and vesicles.
Summary of the parts of the endomembrane system?
- Rough endoplasmic reticulum - studded with ribosomes used to make proteins
- Smooth endoplasmic reticulum - lacks ribosomes but aids in making carbohydrates and lipids
- Golgi apparatus - flattened stacks that process, package and deliver proteins and lipids from the ER
- Lysosomes - membranous vesicles made by the Golgi that contain digestive enzymes
- Vesicles - small membranous sacs used for transport
What is the cytoskeleton?
- A series of proteins that maintain cell shape, as well as anchors and/or moves organelles in the cell
- Made of 3 fibers: large microtubules, thin actin filaments and medium-sized intermediate filaments
What are cilia and flagella?
- Both are made of microtubules
- Both are used in movement
- Cilia are about 20x shorter than flagella
What are cell junctions?
Junctions between the cells of human tissue that allow them to function in a coordinated manner.
3 main types of cell junctions
- Adhesion junctions - mechanically attach adjacent cells (common in skin cells)
- Tight junctions - connections between the plasma membrane proteins of neighbouring cells produce a zipper-like barrier (common in digestive system and kidney where fluids must be contained to a specific area)
- Gap junctions - communication portals between cells. Channel proteins of the plasma membrane fuse, allowing easy movement between adjacent cells.
What do mitochondria do and what do they look like?
- A highly folded organelle in eukaryotic cells
- Produces energy in the form of ATP
- They are thought to be derived from an engulfed prokaryotic cell
Why are enzymes important within cellular respiration and what are their many activities within cells?
- Most enzymes are proteins
- Enzymes are often named for the molecule that they work on and substrates
- Enzymes are specific to what substrate they work on
- Enzymes have active sites where a substrate binds
- Enzymes are not used up in a reaction but instead are recycled
- Some enzymes are aided by non-protein molecules called enzymes
What is enzyme degradation?
A substrate is broken down to smaller products.
What is enzyme synthesis?
Substrates are combined to produce a larger product.
