2- Cells And Cell Theory Flashcards
Are the formation of amino acids, nucleic acids, carbohydrates and lipids sufficient for life by themselves?
No
Do you need living things to make organic compounds?
No
The evolution of cells requires what?
Early organic molecules to assemble into a functional, interdependent unit
What was Stanley L. Miller and Harold C. Urey’s experiment and what did they obtain?
They recreated the primitive oceans and reducing atmosphere (little oxygen) of Earth in the lab.
-They obtained a lot of the basic molecules for life
Amino acids & nitrogenous bases can be created by…
Lightning & primitive oceans
What is the Panspermia hypothesis?
Life came from extraterrestrial origins:
-Life may have originated elsewhere in the solar system or galaxy and arrive on Earth
-In this theory, we would all be descendants from extraterrestrials
Who first observed living cells?
Anton van Leeuwenhoek
What is cell theory?
1) All organisms are made of 1 or more cells
2) Cells are smallest living things — basic unit life
3) Cells only arise by division from a pre-existing
Why are most cells relatively small?
Due to a reliance on diffusion of substances in and out of cells
What is rate of diffusion affected by?
- Surface area available
- Temperature
- Concentration gradient
- Distance
As a cell’s size increases, its volume ________ much more rapidly than its _________
1) increases
2) Surface area
What are the basic structural and functional units of an organism
Cells
What are the main parts of a cell?
1) Plasma Membrane
2) Nucleus
3) Cytoplasm
Characteristics of the plasma membrane?
-Flexible outer surface
-Seperates cell’s internal environment from its external environment
(It is like a container)
Characteristics of the nucleus?
-DNA contains all the information of the cell
-It is surrounded by a membrane
In prokaryote there is no ______, only a circular DNA that is called a _______
1) membrane
2) nucleoid
What are the characteristics of the cytoplasm?
-All parts inside the plasma membrane
-Cytosol: liquid portion of cytoplasm (water + solutes)
-Organelles: biological machines
What is the function of the plasma membrane?
-Encloses a cell and separates its contents from its surroundings
-This separation permits the maintenance of stable chemistry inside the cell
- Allows some substances to move into and out of the cell but stops others (selective permeability)
-Transmits signals between intra and extracellular spaces
What is the structure of the plasma membrane?
-Lipid bilayer (back to back layers made up of phospholipids)
-The thickness of the bilayer is about 5 to 10 nm
-Within the plasma membrane there are proteins (channels, carriers, receptors)
What are organelles?
-Specialized structures inside cells
-Each has a characterized shape and specific function
-8 main organelles of interest
What are the 8 main organelles of interest?
1) Nucleus
2) Endoplasmic reticulum
3) Ribosomes
4) Golgi complex
5) Lysosomes
6) Cytoskeleton
7) Mitochondria
8) Cell membrane
What are the functions of the nucleus?
-Stores genetic material DNA (blueprint)
-‘’Information centre’’
-Contains nucleolus (where ribosome are made)
In eukaryotes, the DNA is divided into multiple ____ chromosomes
Linear
What is the structure of the nucleus?
-Largest organelle in cell (round)
-Is surrounded by a nuclear envelope which is composed of two phospholipid bilayer membranes
-The outer layer of the nuclear envelope is connected to the Endoplasmic Reticulum (ER)
-The nuclear pores allow ions and small molecules to diffuse freely, while controlling the passage of proteins and RNA- protein complexes
What is the function of Ribosomes?
-Site of protein synthesis
-‘’builder’’
What is the structure of Ribosomes?
-Each ribosome is composed of two subunits, each of which is composed by a combination of RNA, called ribosomal RNA (rRNA) and proteins
-Ribosomes can be attached to Endoplasmic reticulum or free in cytosol
-Ribosomes are made in the nucleolus (inside the nucleus)
How do ribosomes make protein?
-They take the m-RNA coming from the nucleus and make a polymer of amino acids named protein
- The sequence of the protein being synthesized determines if the ribosome will become associated with the ER or remain in the cytosol
What are the steps to signalling (protein synthesis
) (5)
1) Signal sequence is synthesized by ribosome
2) Signal sequence binds to signal recognition particle (SRP).
3) Signal recognition particle binds to SRP receptor in ER membrane
4) SRP is released. Protein synthesis continues. Protein enters ER.
5) Signal sequence is removed. Protein synthesis is complete
What is the structure of the Endoplasmic reticulum?
-Network of folded membranes attached to the nucleus
What are the functions of the Endoplasmic reticulum?
-‘’Assembly line’’ (factory)
- Synthesis
- Intracellular transport
What are the 2 types of ER (Endoplasmic reticulum)?
-Rough E.R
-Smooth E.R
What are the characteristics/functions of Rough E.R?
-Covered wth ribosomes
-Involved in protein synthesis
-Proteins can be modified by the addition of short-chain carbohydrates to form glycoproteins
-Those proteins bound for secretion are separated from other products and packaged into vesicles that move to the Golgi for further modification and packaging for export.