Chapter 4- Cells Flashcards
What are 4 basic features of all cells?
- Plasma membrane
- Semifluid substance called cytosol
- DNA molecules called chromosomes (carry genes)
- Ribosomes (make protein)
What are the two types cells?
Prokaryotic
Eukaryotic
Prokaryotic celled organisms exist in what domains??
Domain Bacteria
Domain Archaea
What domains consist of eukaryotic celled organisms?
Protists , Fungi, Animalia, Plantae
What was the first cell type on earth?
Prokaryotes
Prokaryotic cells’ DNA is located where?
The unbound region called the Nucleoid
What don’t prokaryotic cells have?
Membrane bound organelles
In prokaryotes, what is outside the plasma membrane?
A rigid chemically complex cell wall
What does the cellular wall in prokaryotes do?
Protects the cell
Helps maintain its shape
Some prokaryotes have _______.
Surface projections
What is a flagellum, or flagella? What is their function?
Prokaryotic surface projection.
Allows the cell to move.
Some prokaryotic surface projections do what?
Allow prokaryotic cells to join together, or bond to the substrate
Membrane bound organelles exist in what type of cells?
Eukaryotic
Which is larger? Eukaryotes or Prokaryote?
Eukaryote
What are the 3 components of cell theory?
- All living things are composed of one or more cells
- Cells are the basic units of structure and function in an organism
- Cells come only from existing cells
All living things are composed of _______.
One or more cells
Cells are the basic unit of __________ in an organism.
Structure and function
Cells come only from where?
Existing cells
How big is a human red blood cell?
8 micrometers in diameter
8x(10^-6) meters
What is the smallest cell in the human body?
A sperm cell
Why are cells small?
Because cells are small, they have a higher surface area to volume ratio, allowing for substances to quickly diffuse into and out of a cell
How big is bacteria? Example Eschericia coli (E. coli)
1 X 3 micrometers
What is the formula for surface area?
SA= 6 X (A^2)
SA= 6(sides) X (area of one side squared)
What is the formula for volume?
V= a^3
Volume= length of one side cubed
How high can an electron microscope magnify?
1,000X
Can a compound light microscope see living cells?
Yes
Can an Electron microscope see living cells?
No…it kills the cells being observed
Eukaryotic cells have what type of organelles?
Membrane bound
Eukaryotic cells are ______ than prokaryotic cells.
Larger
When did prokaryotic cells first appear?
3.5 BYA (billion years ago)
When did the first eukaryotic cells appear?
2.0 BYA (billion years ago)
The nucleus is like the _____?
Control center
The cytoskeleton is the ______.
Structure
The Golgi Complex is the ______.
Distribution Center
The lysosomes are like the _____.
Cleaning crew
The endoplasmic reticulum is like the _____.
Assembly Line
The mitochondria are like the _____.
Powerhouses
The ribosomes are like the ______.
Workbenches
The cell membrane is like the _____.
Security gate
The nucleus contains the cell’s _____.
Genetic information
What is the nucleolus?
A prominent structure within the nucleus
The site of ribosomal RNA (rRNA) synthesis
What encloses the nucleus?
The nuclear membrane or nuclear envelope
What does the nuclear envelope consist of?
2 separate phospholipid bilayers with associates proteins
What is the function of the nuclear envelope?
Similar to the plasma membrane, the nuclear envelope regulate passage of material to and from the nucleus.
The nuclear envelope is perforated by what?
Protein lined pores
What do the protein lined pores of the nuclear envelope do?
Regulate entry and exit of large molecules AND
Connect with the cell’s network of membranes called the Endoplasmic reticulum
How is rRNA formed?
Synthesized in the nucleolus according to instructions in the DNA.
How are the subunits of ribosomes formed?
In the nucleolus, proteins are brought in from the cytoplasm and joined with rRNA. They then exit to the cytoplasm the join with other subunits to form function ribosomes
What are the 2 types of RNA?
Ribosomal RNA (rRNA) Messenger RNA (mRNA)
What is mRNA?
What does it do?
Messenger RNA is a transcription of protein synthesizing instructions written in the gene’s DNA.
mRNA moves into the cytoplasm where ribosomes translate it into amino acid sequences of proteins.
What do ribosomes do?
They use the instructions written in the Nucleus by the DNA in the form of mRNA to synthesize amino acid chains to build proteins.
Where can ribosomes be found?
Free ribosomes are suspended in the cytosol
Bound ribosomes are found attached to the outside of the endoplasmic reticulum or the nuclear envelope
What are the two types of ribosomes?
Free ribosomes
Bound ribosomes
How many types of ribosomes are there?
2
What is the purpose of the central vacuole in plant cells?
- Regulates composition of the cytoplasm
- Creates the internal pressure characteristic of plant cells
- Stores various compounds produced by the cell
The endoplasmic reticulum is a _____.
Biosynthetic workshop
How many types of endoplasmic reticulum (ER) are there?
What are they?
- Smooth ER
2. Rough ER
What is characteristic of the Smooth ER?
It lacks attached ribosomes
What is characteristic of Rough ER?
Has bound ribosomes attached to its outer surface of the membrane.
What are the functions of the Rough ER?
Protein synthesis
Protein movement
Protein “proofreading”
Why do we become resistant to drugs and other substances, resulting in increased dosage to get same effects?
As our liver cells are exposed to chemicals, the amount of smooth ER increases as does its detoxifying chemicals. The rate of detoxification increases resulting in increased tolerance to the drug.
The growth of smooth ER in response to one drug can lead to what?
Increase the need for higher doses of other drugs
Barbiturate abuse results in what, relative to other drugs?
Decreased effectiveness of certain antibiotics and other useful drugs
What are the functions of the Smooth ER?
- Synthesis of Lipids: oils, phospholipids, and steroids
- Processing drugs, alcohol l, and other harmful substances
- Storage of Ca ions (calcium ions)
What is a glycoprotein?
Short chains of sugar linked to the polypeptides of proteins during synthesis by the ribosomes
Explain the steps involved with making a protein.
- mRNA, transcribed from DNA in the nucleolus) is read by bound ribosomes of the Rough ER.
- A short sugar chain is often attached to the protein polypeptide, creating a glycoprotein.
After a protein is formed by the ribosomes of Rough ER, what occurs to the protein?
It is then transported to the Golgi Apparatus
What does the Golgi Apparatus do?
Modifies, sorts, and ships cell products
The Golgi Apparatus serves as a _______.
Molecular warehouse and processing station for products manufactured by the ER.
Products travel in transport vesicles from what to what?
ER to Golgi apparatus
One side of the Golgi stack serves as what?
Docking station for transport vesicles from the ER
Unlike the ER, Golgi sacs are ________.
Not connected
What happens when a transport vesicles arrives at the Golgi Apparatus
It fuses with Golgi sac, adding it’s membrane and contents to the receiving side of the Golgi apparatus
As products (proteins) move through the Golgi Apparatus, what occurs?
They are modified
The shipping side of the Golgi apparatus does what?
Dispatches its’ products in vesicles that travel to other sites
What sort of modifications may a protein from the ER undergo in the Golgi apparatus? (2)
- Carbohydrates portions of the glycoproteins are modified, removing some sugars and substituting others
- Phosphate groups may be added to help the Golgi sort molecules into different batches with different destinations
Vesicles from the Golgi go where?
To the plasma membrane for transport outside the cell
What is a second thing that may occur to finished Golgi products?
They may become part of the plasma membrane or other organelle, such as lysosomes
What are lysosomes?
The digestive compartments of cells
What are the functions of lysosomes?
- Fuse with food vacuoles and digest food
- Help white blood cells destroy bacteria
- Fuse with other vesicles containing damaged organelles or other material (small amounts of cytosol) to be recycled within a cell
What exactly is a lysosomes?
A membrane enclosed sac of digestive enzymes
Where are lysosomes made?
Enzymes and membrane of the lysosomes are made by the Rough ER, then processed through the Golgi
The lysosomes provide an ________ environment for enzymes while _______ them from the rest of the cell.
Acidic
Isolating
How do lysosomes continually renew a cell?
Materials fused with a lysosomes are chemically broken down to be used again
Tay-Sachs disease is an example of what?
A lipid-digesting enzyme is missing causing brain cells to become impaired by the accumulation of lipids
Lysosomal storage problems are _______.
Rare
What are vacuoles?
Large vesicles that have a variety of functions
Some protists have _________ vacuoles, which help _________.
Contractile
Eliminate water
In plants, what are some functions vacuoles may serve?
Have digestive functions
Contain pigments OR
Contain poisons that protect the plant
What are the components of the endomembrane system?
Nuclear Envelope Endoplasmic Reticulum Golgi Apparatus Lysosomes Vacuoles Plasma membrane
The mitochondrion are the _______ of the cell.
Powerhouse
Only animals have mitochondria. T/F
F- plants can have them too
The chloroplast is like the ________ of the plant cell.
Solar panel
Only plants have chloroplasts. T/F
T
What do mitochondria and chloroplasts both contain?
DNA
Ribosomes
What is the cytoskeleton?
A network of protein fibers which organize the structures and activities of the cell
How did mitochondria and chloroplasts evolve?
They evolved by endosymbiosis.
The structure of DNA and ribosomes in mitochondria and chloroplasts is very similar to what?
Prokaryotic cells
What membranes form a mitochondrion?
Outer membrane
(Intermembrane space)
Inner membrane
The inner membrane of the mitochondrion encloses what?
The mitochondrial matrix
What is within the mitochondrial matrix?
Contains:
Mitochondrial DNA and ribosomes
Enzymes that catalyze some of the reactions of cellular respiration
The inner and outer membrane layers are composed of what?
A phospholipid bilayer with a unique collection of embedded proteins
What is the singular of mitochondria?
Mitochondrion
What are two features of the inner mitochondrial membrane?
- Highly folded
- Embedded with protein molecules that function in ATP synthesis?
The folds of the inner mitochondrial membrane are called what?
Cristae
What is the purpose of the folds of the cristae?
To increase the membranes surface area thus enhancing the mitochondrion’s ability to produce ATP
What is embedded within the cristae?
Many protein molecules that function in the synthesis of ATP
What are chloroplasts?
The photosynthesizing organelles of plants and algae.
What is photosynthesis?
The conversion of light energy from the sun, into the chemical energy of sugar molecules.
In a chloroplast, the inner membrane contains what?
- a thick fluid called Stroma
What is the thick fluid called that is contained within the inner membrane of a chloroplast?
Stroma
Stroma contains what?
Chloroplast DNA
Ribosomes
Many enzymes
What is suspended within the Stroma?
Thylakoids
What are thylakoids?
The cells solar power packs.
The site where green chlorophyll molecules embedded in the thylakoids membranes trap solar energy
The interconnected web of thylakoids are located where?
Suspended within the Stroma of a chloroplast.
Which membrane within a chloroplast appears to be the most extensive?
The Thylakoid membrane
What are embedded within the thylakoids?
The chlorophyll molecules that trap solar energy
What does the endosymbiont theory state?
That mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells.
How did prokaryotic mitochondria/chloroplasts gain access to larger cells?
Maybe as undigested prey or parasites.
How would a host cell benefit from the endosymbiont, mitochondria/chloroplast?
In an increasingly aerobic environment due to O2 created by photosynthetic prokaryotes, the host cell would benefit from a symbiont that uses oxygen to release large amount of energy from organic molecules.
Over the course of evolution, the host cell and its symbiont ________.
Merged into a single organism, becoming a eukaryotic cell with mitochondria/chloroplast
What occurred if a host cell enveloped a photosynthetic prokaryote?
The photosynthetic prokaryote would provide the cell with food, nourishment.
The first endosymbiosis would have given rise to what?
A eukaryotic cell with mitochondria.
The fibers that make up the cytosketeleton acts as what?
A skeleton that provides structure and mobility for cells
The interaction of what two things must occur for cell mobility, internally and externally?
Interaction between the cytoskeleton and motor proteins
What are the 3 main fibers, order thickest to thinnest) that make up the cytoskeleton?
Micro-tubules (Thickest)
Intermediate filaments (Medium)
Microfilaments (thinnest)
What are microtubules?
Straight, hollow tubes composed of globular proteins called Tubulins.
What is Tubulin?
The globular protein microtubules are composed of
How do microtubules elongate?
By the addition of tubulin protein
In animal cells, where do microtubules grow from?
A region called the Centrosome
What is the width of a microtubules?
25 nm
What is the width of intermediate filament?
10 nm
What is the width of microfilament?
7 nm
The centrosome contains what?
A pair of centrioles
What are the centrioles comprised of, located in the Centrosome?
Each composed of a ring Of microtubules
What is the function (4) of microtubules?
Microtubules shape and support the cell
Act as tracks along which organelles equipped with motor proteins move.
Guide the movement of chromosomes when cells divide
Main component of cilia and flagella
Intermediate filaments are made of what?
Various fibrous proteins that supercool into cables
What is the purpose of intermediate filaments?
Reinforce cell shape
Anchor some organelles
Intermediate filaments are more _______ structures in the cell.
Permanent
Microfilaments are also called _____?
Actin filaments
What is the composition of microfilaments?
Solid rods composed of globular proteins called actin, arranged in a twisted double chain
What purpose do microfilaments serve?
Form a three dimensional network inside the plasma membrane to help support the cell’s shape
Involved in cell movement
What causes muscle contraction?
When actin filaments interact with a thicker filament consisting of motor proteins called myosin, causing contraction of muscle cells (sliding filament theory)
How do cilia and flagella move?
When microtubules bend
What are cilia?
The numerous protusions that propel a Protista, such as paramecium
What is the singular of cilia?
Cilium
Some protists may move using what?
Flagella (one, or a few per cell)
Can multicellular organisms’ cells have cilia or flagella?
Yes
Cilium May also serve as what?
Signal receiving antenae
Cilia and flagella are composed of what?
Microtubules wrapped in an extension of the plasma membrane
How is a flagella or cilia structured in eukaryotic organisms?
A ring of 9 microtubule doublets surrounds a central pair of microtubules
(9+2 Pattern)
How is the microtubule assemble of the flagella or cilia anchored?
Anchored in the cell by a nasal body structurally similar to the centriole
What are the large motor proteins?
Dyneins
How are the microtubule doublets in a flagella/cilia held together?
Held together by flexible cross linking proteins
What causes the microtubules to bend?
The coordinated walking ”of the two footed dynein protein along adjacent doublet causing the microtubule doublets, and ultimately the flagella/cilia, to bend
Cilia with the purpose of receiving signals, is ________. Why can’t it bend?
Non-motile
It can bend because it lacks the central microtubule doublets
How many cilia with antenna capability can exist per cell?
One
In vertebra, all cells have a _______ cilium.
Primary
What is the primary cilium used for?
Important to
Embryonic development
Sensory reception
Cell function
Defective cilia have been linked with what?
Poly cystic kidney disease and other human disorders
What is the rare condition of Primary Ciliary Diskinesis (PCD)?
Cilia and flagella lack motor proteins
How is PCD characterized?
Recurrent respiratory tract infections and immobile sperm
Without motor proteins, microtubules ________.
Cannot bend
What is the extracellular matrix (ECM)?
- An elaborate exo-layer helping hold cells together within tissues.
- Protects and supports the plasma membrane
What are the main components of the ECM?
Glycoproteins (proteins bonded with carbohydrates)
_________ synthesize and secrete an elaborate _________.
Animal cells Extracellular matrix (ECM)
What is the most abundant glycoprotein?
Collagen
What does collagen do?
Forms strong fibers outside of the cell
Collagen accounts for what percentage of the protein in our body?
40%
Where does the extracellular membrane (ECM) exist?
Between animal cells
The ECM may attach to the cell through other ________ that then bind to _______.
Glycoproteins
Integrins
What are integrins?
A membrane protein that spans the membrane, attaching on the other side to proteins connected to microfilaments of the cytoskeleton
What is the function of integrins?
Integration
Transmit signals between ECM and cytoskeleton
Can communicate changes in/out of the cell
What are two various functions of the ECM?
Can regulate a cell’s behavior by directing the path along which embryonic cells move.
Can influence the activity of genes through the signals it relays
How many types of cell junctions are found in human tissue?
3
What are the 3 types of junctions in animal tissues?
Tight junction
Anchoring junction
Gap junction
What occurs at tight junctions of animal tissues?
The plasma membranes of neighboring cells are knit tightly together by proteins
What does a tight junction prevent?
Prevents leakage of fluid across a layer of cells
How do anchoring junctions function?
Like rivets, fastening cell’s together into strong sheets
Anchoring junctions are common in what type of tissue?
Tissues subject to stretching or mechanical stress, such as skin and muscle.
Intermediate filaments, made of strong proteins, do what to anchoring junctions?
They anchor these junctions in the cytoplasm.
Gap junctions are AKA ______.
Communicating junctions
What are gap junctions?
Channels that allow passage of small molecules through protein lined pores between cells
In heart muscles, gap junctions are used how?
Allowing the flow of ions between cells, coordinating their contraction.
Gap junction are common in ______. Why?
Embryos
Because communication between cells is essential for development
What is the one feature that distinguishes plant from animal cells?
Cell wall
The cell walls of plants are composed of what?
Cellulose fibers embedded in a matrix of proteins and polysaccharides
What exists between adjacent plant cells?
A layer of Pectin (sticky polysaccharides) which glues the cell together.
When a cell stops growing, what does it do?
Strengthen its walls
Some cells add a secondary cell wall deposited in _________.
Laminated layers next to the plasma membrane
Wood consists mainly of what type of walls?
Secondary walls
What are the numerous channels that connect adjacent plant cells called?
Plasmodesmata (singular Plasmodesma)
Cytosol passing through the plasmodemata allows _______.
Water and other small molecules to move freely from cell to cell
Plasmodesma allow plant cells to ______.
Share water, nutrients, and chemical messages.
What is the globular protein that microtubules are made from?
Tubulin
