Unit 2: Cells Flashcards
What is the difference between light and electron microscopes?
Light: pass visible light through a specimen and glass lenses bad light to magnify the image and project it to the viewers eye
Electron: use a beam of electrons
What is the difference between scanning electron microscopes and transmission electron microscopes?
Scanning electron microscopes: study the detailed architecture of cell surfaces
Transmission electron microscopes: study details of internal cell structure
Cell Theory
States: all living things are composed of cells and all living cells came from other cells
Do large cells have more/less surface area than small cells? How is it related to their volume?
Large cells have more surface area compared to small cells, but less related to their volume
What sets limits on a cells size?
The functions it must carry out. A cell must AT LEAST (minimum size)be able to house enough DNA molecules protein molecules, and internal structures to survive and reproduce. AT MOST (maximum size) a cell should have enough SA to get enough nutrients and oxygen and dispose of waste. Size is also limited to the distance materials must diffuse within a cell
What are the two types of cells found on earth?
Prokaryotic and eukaryotic
What kingdoms are found in both types of cells?
PROKARYOTIC: bacteria
EUKARYOTIC: plants, animals, fungi, and protists
What are 4 things all cells have in common?
- All bounded by a plasma membrane
- Have chromosomes carrying genes made of DNA
- Contain ribosomes
- Made of protein
Which type of cell (prokaryotic/eukaryotic) is usually bigger?
Eukaryotic
Nonmembranous organelles
- no membrane
- direct contact with the cytosol
- includes the cytoskeleton, microvilli, centrioles, cilia, ribosomes and proteasomes
Membranous organelles
- covered with phospholipid membrane
- isolated from the cytosol
- includes the ER, nucleus, Golgi apparatus, lysosomes, Peroxisomes, and mitochondria
Cytoplasm
Entire region between the nucleus and the plasma membrane
Chromosomes
Carry genes made of DNA. Has information for making proteins
Ribosomes
Makes proteins according to instructions from genes
Nucleus
Contains and protects genetic material (DNA)
Controls cells activities by directing protein synthesis
DNA in prokaryotes is round
DNA in eukaryotes is thread-like
Nucleoid
Where the DNA of a prokaryotic cell is contained. In a eukaryotic cell, there is not membrane that surrounds the DNA.
Flagella
Propels the prokaryotic cell through its liquid environment
4 differences between prokaryotic and eukaryotic cells
PROKARYOTIC:
- small
- no nucleus that stores DNA
- No membrane-enclosed organelles
- smaller and different ribosomes
EUKARYOTIC:
- larger
- membrane enclosed organelles
- has a nucleus
What are organelles?
Small organs that are membrane bound structured that perform specific functions in the cell
What are the 4 main functions carried out by organelles in the cells?
- Manufacturing (nucleus, ribosomes, ER, Golgi apparatus)
- Breakdown (lysosomes, vacuoles, peroxisomes)
- Energy (mitochondria, chloroplast)
- Structure/movement/communication (cytoskeleton, plasma membrane, cell wall)
Which structures are found in plant cells but not animal cells?
Central vacuole, chloroplast, cell wall, plasmaodesmata)
Cell wall
What is its function?
What is it made of?
Around the plasma membrane
Protects cells and maintains their shape
Composed of cellulose
Chloroplasts
Performs photosynthesis
What is the importance of the central vacuole in plant cells?
Store water and other various chemicals
What is the cell membrane mainly composed of?
Phospholipids
Have hydrophilic phosphate group head and a nonpolar hydrophobic fatty acid tail
Form a 2 layer sheet called a phospholipid bilayer
Heads face outward while the tails face inward
What other macromolecules are found in the plasma membrane?
Proteins
Nuclear envelope
Encloses the nucleus
Has protein lined pores
Nucleolus
What is synthesized here?
Prominent structure in the nucleus Ribosomal RNA (rRNA)
Ribosomes carry out…
Why would the pancreas have a lot of ribosomes?
Protein synthesis
Because they produce digestive enzymes
What is the difference between free and bound ribosomes?
Free ribosomes: suspended in the fluid of the cytoplasm
Bound: attached to the outside of the ER or nuclear envelope
What is a vesicle?
Sacs made of membranes
What does the smooth ER synthesize? What does it store?
Synthesizes lipids. Contains digestive enzymes, which is why the liver has a lot
Stores calcium ions
Function of the rough ER.
To make more membrane. Attached ribosomes produce proteins that are inserted into the ER membrane, transported to other organelles, or secreted by the cell. Folds protein structures. Synthesizes proteins and glycoprotein (sugar + proteins)
Steps of synthesizing and packaging proteins in the rough ER
- Polypeptide is synthesized by bound ribosomes and threaded into the cavity of the rough ER through pores and is folded into a 3D shape
- Short chains of sugar are linked to polypeptides, making it a glycoprotein
- When a molecule is ready to be exported fro, the ER its packaged to a transport vesicle that moves it from one part of the cell to another
- Vesicle buds off from ER membrane and travels to the Golgi apparatus for more processing. Then, a transport vesicle that has the finished molecule will take it to the plasma membrane and release its contents from the cell.
Golgi apparatus
Function
Are they interconnected?
Consists of flattened says stacked on top of each other.
Sorts, processes and transports proteins
NOT interconnected
In the Golgi apparatus, how are the finished products packaged? What are 3 things that could happen to the finished product?
Packaged in transport vesicles.
- Could be exported for the cell
- Could b part of the plasma membrane
- Could become a part of another organelle
Lysosomes
Have digestive enzymes enclosed in a membranous sac
Important in digestion, autophagy (clean up inside cells/damaged organelles) and autolysis (the destruction of cells or tissues by their own enzymes)
Vacuoles
Food vacuoles vs. central vacuoles
Membranous sacs that have a variety of functions
Food vacuole: breaks down cells and releases nutrients to the cell
Central vacuole: has hydrolytic functions, help cells grow by absorbing water. Stores important chemicals or waste products
Peroxisomes
An organelle that breaks down fatty acids to be used as fuel and detoxifies alcohol and other harmful substances
Mitochondria
Carries out cellular respiration in most eukaryotic cells by converting the chemical energy of food into the chemical energy, ATP
Has 2 membranes and 2 internal compartments
Cristae
Folds in inner membrane with protein molecules that make ATP in it. The folds increase surface area,enhancing mitochondria’s ability to make ATP
Chloroplasts
How many membranes does it have?
Photosynthesizing organelles of all photosynthetic eukaryotes.
Has 2 membranes
Inner membrane has a thick fluid called stroma
Inside, there is a network of interconnected sacs called thylakoids p, stacks are called granum
Endosymbiosis
Theory states: mitochondria and chloroplasts used to be small prokaryotes that began living within large cells. May have gained entry to the larger cells as un digested prey or internal parasites
Cytoskeleton
Network of protein fibers extending through the cytoplasm of the cell. Gives structure and mobility.
Microfilaments
Composed of globular protein (actin) arranged in a double twisted chain.
Not permanent
Smallest part of the cytoskeleton 7-9 nanometers
Works in muscle contractions, helps cytoskeleton move, helps in punching before cells divide
Involved in cell movements
Intermediate filaments
Rope like structure made of fibrous proteins. Reinforce cell shape and anchors organelles.
Permanent
Suspends organelles
Microtubules
Straight hollow tubes made of globular protein-Tubulins. Elongate by adding subunits-cables to transport organelles
Biggest 25 nanometers
Attaches to chromosomes for cell division
Not permanent
9 X 2 array
Cilia vs flagella
Cilia: small tails that propel the cell
Flagella: longer, found in many protists
Steps of producing and shipping a protein
- Nucleus
- Ribosomes
- Rough ER
- Golgi apparatus-can then become a lysosome, be excreted from the cell, or become part of the membrane
What are two advantages of compartmentalization?
- Surface area
2. Specialization
Can you have multicellular or single cellular prokaryotes and eukaryotes?
You CAN’T have multicellular prokaryotes
You can have multi and single celled eukaryotes
What is the importance of the extra cellular matrix?
What are the main components?
Holds cells together. Protects and supports plasma membrane
Glycoproteins (protein and carbohydrates)
What are integrins? Where are they found and what is their function?
Membrane proteins attached to the ECM. Span the membrane, attach to the other sore of proteins connected to the Microfilaments. Transmit information between the ECM and cytoskeleton
How do neighboring cells adhere, interacts, and communicate?
Through specialized junctions
3 types of junctions
- tight junctions: membranes of cells are pressed tightly against one another, knit together by proteins. Prevent leakage of extra cellular fluid with a sheet of tissue
- anchoring junctions: fastens cells together into strong sheets, intermediate filaments anchor them to the cytoplasm
- gap junctions: channels that let small molecules flow through protein lined pores of cells.
Capsule
Jelly-like outer coating of many prokaryotes
Plasmodesmata
Channels between adjacent plant cells, form circulatory and communication system connecting cells in plant tissues. Cells share water, food, and chemical messages.
