Unit 2: Cell Structure and Function
Identify and describe two examples of specialized surfaces for exchanging materials with the surrounding environment
- Root hair extensions on roots increase absorption on nutrients and water from soil - Microvilli extensions on cells that line the gut increase absorption of nutrients in small intestine Numerous tiny air sacs (alveoli) increase gas exchange in lungs
What type of surface area to volume ratio is most favorable for cells?
A higher surface area-to-volume ratio is more efficient for exchange of materials with the environment
What is the structure of the vacuole?
A membrane-bound organelle that is generally small and circular in structure.
How does the ribosome demonstrate a common ancestry of all known life?
All life forms have ribosomes.
Identify three similarities between a prokaryotic and eukaryotic cell.
Cell membrane, Ribosomes, store hereditary information
What is the function of steroids in the plasma membrane?
Cholesterol helps to control membrane fluidity and allows the cell membrane to adapt to different environmental conditions; at moderate temps cholesterol will reduce membrane fluidity and at low temps it stops the phospholipids from packing too closely together
What is the function of the contractile vacuole?
To maintain the constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations in a well-balanced way so that the cell doesn't get ruptured due to cytolysis. (Osmoregulation)
What is active transport?
Type of membrane transport that requires energy to move substances across cell membranes against their concentration gradient examples: - Sodium-Potassium pump- Uses energy from ATP to move 3 Na+ ions out of cell and 2 K+ ions into cell Used to create membrane potential in animal cells - Endo/Exocytosis- Uses energy and membrane vesicles to transport molecules across cell membranes
How are the food materials brought in by endocytosis digested?
Vesicles carry materials into the cell and lysosomes release digestive enzymes to break them down
What is a concentration gradient?
When the amount or concentration of particles is higher in one area than another
What is the function of an ATPase?
an enzyme that removes a phosphate group from ATP releasing energy
What is the structure of the inner membrane (cristae) of the mitochondria?
highly folded membranes
How does that contribute to the function of the inner membrane (cristae) of the mitochondria?
highly folded membranes allow for more surface area to complete the oxidative phosphorylation of cellular respiration
What is the function of the endoplasmic reticulum's folded membrane?
increase surface area
What is the function of the inner membrane folding in the mitochondria?
increase surface area and to allow for a concentration gradient for oxidative phosphorylation
What is the function of thylakoid membranes in the chloroplast?
increase surface area and to allow for a concentration gradient for oxidative phosphorylation
How do membrane-bound organelles allow for compartmentalization of the cell and its functions?
it allows for more efficient processes because molecules and enzymes necessary for a specific function are found in specific organelles
How does the endoplasmic reticulum provide mechanical support?
it can help maintain cell shape by interacting with the cytoplasmic matrix
How does the endoplasmic reticulum aid in protein synthesis?
it has ribosomes on it to perform protein synthesis
Describe the process of exocytosis.
molecules are expelled from the cell by a vesicle approaching the cell membrane and fusing with the membrane to release the contents outside of the cell
Where are plasma membranes found in a cell?
surrounding the cell and also around many different organelles
How does the vacuole provide turgor pressure?
the vacuole will fill up with water that pushes on the cell membrane which then pushes on the cell wall causing turgor pressure
How did membrane bound organelles originate in eukaryotic cells?
through endosymbiosis
How does the membrane of organelles allow for specific processes to take place?
Inside of eukaryotic cells are multiple membrane bound organelles such as the mitochondria, chloroplast, vacuoles, nucleus, etc.
How does the structure of the rough ER aid in the function?
It allows for the production, folding, quality control and dispatch of some proteins.
What is the endosymbiotic theory?
Organelles like mitochondria and chloroplasts were once free-living prokaryotes
How is a concentration gradient maintained?
Particles moving through transport or channel proteins
Where do the light-dependent and light-independent reactions take place?
Photosystems and ETC for the light independent reactions are located in the thylakoid membranes. Light independent reactions happen in the stroma.
What is the structure and function of a chloroplast?
Plant cell organelle that is oval-shaped and has an outer membrane and inner membrane folded into thylakoid sacs stacked into grana that converts light energy into chemical energy through the process of photosynthesis.
Where does the electron transport chain in cellular respiration take place?
Proteins for ETC are located in cristae membranes
Identify an example of a material that would require exocytosis
Secretory proteins, hormones, waste products
What does it mean if a solution is hypertonic?
Solute concentration of a solution is greater than the cell it surrounds
What does it mean if a solution is hypotonic?
Solute concentration of a solution is lower than the cell it surrounds
Where is ATP synthesized in photosynthesis?
Stroma of chloroplast
What is the structure and function of the Golgi?
The Golgi apparatus is a central intracellular membrane-bound organelle. Its key function is to traffic, process, and sort newly synthesized membrane and secretory proteins and lipids.
How does the phospholipid bilayer maintain the internal environment of a cell?
The cell membrane acts as a barrier between the interior and exterior cellular environment It is selectively permeable and controls and maintains a balance of molecules that are present in the cell, such as proteins and ions
Define the fluid mosaic model.
The cell membrane is a mosaic of protein molecules floating within a fluid bilayer of phospholipids.
How does the structure of the mitochondria aid in the function?
The inner membrane folds increase surface area which allows for a lot of ATP to be formed and quickly.
How does the thylakoid aid in energy storing?
Electron transport proteins are located in thylakoid membrane and transport of H+ ions into the thylakoid space creates the H+ gradient needed for ATP production during the light dependent reactions.
What is required for active transport?
Energy (ATP)
Where is ATP synthesized in cellular respiration?
- 2 ATP made during glycolysis in cytoplasm - 2 ATP during Krebs cycle in matrix of mitochondria - 32 made by ETC/ATP synthase on matrix side of cristae
Identify three differences between a prokaryotic and eukaryotic cell.
- In eukaryotic cells, DNA is linear and is found in the nucleus. - DNA in prokaryotes is circular and found in cytoplasm Euk. cells have other membrane-bound organelles. Prokaryotes- no membrane bound organelles Euk. cells are generally larger. Prokaryotes are always unicellular. Eukaryotes may be multi- or uni-cellular.
Identify and describe two examples of strategies that organisms use to obtain nutrients and eliminate wastes.
- Obtain nutrients - Autotrophs (phototroph or chemotroph) and heterotrophs - Eliminate wastes - removal of nitrogenous wastes varies - ammonia, urea, uric acid
What are the three types of RNA involved in the structure or function of the ribosome?
- messenger (mRNA) is transcribed from DNA and carries the message to cytoplasm where ribosomes translate it into a polypeptide - transfer (tRNA): carries a specific amino acid to the correct position on the ribosome using its anticodon to match to the codon on the mRNA. - ribosomal (rRNA): joins with proteins to make ribosomes where translation occurs to form a protein.
How does the membrane of organelles allow for enzymatic processes to take place?
By having the organelles separate from the cytosol the enzymes used to break down carbohydrates for example are able to work at a specific pH that would not be able to function if it were free floating in the cytosol. By having the membranes allows each enzyme to have a specific pH and specific function for making lipids, breaking down sugars, etc.
How does the cell wall protect the cell from hypotonic solutions?
Cell walls prevent plant cells from bursting when placed in hypotonic solutions.
How does the thylakoid aid in energy capturing?
Chlorophyll containing photosystems are located in thylakoid membrane and numerous thylakoid sacs create more surface area to collect more light
What causes a concentration gradient?
Differences in the amount of substances on either side of a membrane
What types of cells have a cell wall?
Fungi, plants, prokaryotes
How can an increase in surface affect heat exchange?
Higher surface area = higher heat exchange
What is the function of glycoproteins in the plasma membrane?
Important in cell to cell recognition and adhesion
What is the function of the central vacuole?
In plants it helps to maintain water balance.
What is the structure and function of the smooth ER?
It is a network of membranes called cisternae. They are held together by the cytoskeleton. The function of the smooth ER is to help with synthesizing lipids, phospholipids as in the plasma membrane and steroids.
What is the structure and function of the lysosome?
It is a small membrane bound organelle that has an acidic interior. The purpose of the lysosome is to break down excess or worn-out cell parts. They can also aid in destroying invading viruses and bacteria.
What is the structure and function of the mitochondria?
It is membrane bound organelle that consists of an outer and inner membrane that produces energy for the cell by breaking down carbohydrates and producing ATP.
What is the function of the food vacuole?
It is used for storage of nutrients, water or waste.
How does the structure of the Golgi aid in the function?
It packages proteins into vesicles so they can be transported in or out of the cell.
How do large amounts of water pass through the membrane?
Larger amounts of water can pass through the membrane more quickly via membrane channel proteins called aquaporins
What is water potential?
Potential energy of water in a system; tendency of water to move from one area to another due to osmosis
Where does the electron transport chain in photosynthesis take place?
Proteins for ETC are located in thylakoid membranes
What is the relationship between the ribosome and the rough ER?
Ribosomes attach to the rough ER and insert the proteins being made into the rough ER for intracellular transport to Golgi for modification and export
What is the structure and function of the ribosome?
Ribosomes consist of RNA and proteins and they help with synthesizing proteins. There is a large and small subunit.
How does the structure of the lysosome aid in the function?
The membrane surrounding the lysosome keeps proteolytic enzymes separated from the rest of the cell. Proton pumps in lysosomal membranes create acidic interior for digestion.
What is the structure and function of the rough ER?
The rough endoplasmic reticulum is a series of connected flattened sacs, part of a continuous membrane organelle within the cytoplasm of eukaryotic cells, that plays a central role in the transport of proteins made on its attached ribosomes.
How does the structure of the ribosome aid in the function?
The structure of the ribosome allows proteins to be made inside or outside the cell.
How does surface area to volume ratio affect the size of the cell?
The surface area of the plasma membrane must be large enough to adequately exchange materials. As a cell increases in size its surface area/volume decreases, limiting how big it can get.
What types of materials require a protein to pass through the membrane?
They are large and/or polar molecules that cannot easily pass through the nonpolar region of the membrane examples: glucose, ions
How do large polar molecules pass through the membrane?
Through carrier proteins
How do charged molecules or ions pass through the membrane?
Through protein channels
How does the structure of the chloroplast aid in the function?
Thylakoid sacs make compartments to create the H+ gradient needed for ATP production during the light dependent reactions.
What is passive transport?
Type of membrane transport that does not require energy to move substances down their concentration gradient across cell membranes. examples: - Simple diffusion- movement of oxygen from alveoli into blood stream - Facilitated diffusion - movement of glucose across a cell membrane via a carrier protein - Osmosis- movement of water across a cell membrane with the help of aquaporins
What is endocytosis? Describe the three types of endocytosis.
When large particles enter a cell in vesicles Phagocytosis (cell "eating"), pinocytosis (cell "drinking"), receptor-mediated endocytosis (receptors on cell will allow for only specific molecules to be taken into vesicles; ex: cholesterol)
What is exocytosis?
When large particles exit a cell in vesicles.
What types of materials require a vesicle for export or a food vacuole for import?
bulk transport or larger molecules (requires bulk transport because too many of them to efficiently cross the membrane or too large to fit through the membrane)
What composes the cell wall of a plant?
cellulose
What composes the cell wall of a fungi?
chitin
How can a cell increase surface area without increasing the volume?
folded membranes
What is the function of the multiple membranes and sacs found in the Golgi?
increase surface area for distribution of proteins, etc.
How does the lysosome aid in intracellular digestion?
it will break down food using its enzymes
How does the lysosome aid in recycling the cell's organic materials?
it will breakdown old or broken down organelles using its hydrolytic enzymes
How does the Na + /K + ATPase maintain the membrane potential?
it will pump 3 Na+ out of the cell for every 2 K+ that it pumps into the cell which will keep the inside less positive than the outside
How does the endoplasmic reticulum aid in intracellular transport?
it will transport materials through vesicles
How does the lysosome aid in apoptosis (programmed cell death)?
lysosomes can release enzymes called proteases into the cytosol that will start the cascade of apoptosis
How is the chloroplast organized?
many thylakoid membranes stacked to increase surface area for light reactions in photosynthesis
Describe the process of endocytosis.
molecules are moved into the cell by the cell membrane surrounding them and pinching off to create a vesicle inside the cell
Describe the process of passive transport.
molecules move from an area of high concentration to an area of low concentration with no energy needed
Describe the process of facilitated diffusion.
molecules move from high to low concentration through a protein
Describe the process of active transport.
molecules move from low to high concentration with energy required
How does the cell wall maintain cell structure?
provides a framework for the cell through an interconnected network of cellulose fibers, structural proteins, and other polysaccharides that help maintain the shape
How does the vacuole assist in storage of macromolecules?
provides a lot of space for storage of many types of macromolecules
How is a prokaryotic cell compartmentalized?
DNA is usually free floating in cytoplasm
How does an increase of surface area affect the increase in volume?
As cells increase in size volume increases faster than surface area. The relative surface area decreases and the demand for internal resources increases.
How are simple diffusion and facilitated diffusion similar?
Both are kinds of passive transport (no energy required) Both move molecules down their concentration gradient from high to low
How is a eukaryotic cell compartmentalized?
DNA contained in nucleus, other membrane-bound organelles with compartmentalized functions
What is the function of glycolipids in the plasma membrane?
Maintain stability of cell membrane and serve in cellular recognition
What is osmoregulation?
Maintaining constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations.
Where does the citric acid cycle (Krebs cycle) in cellular respiration take place?
Matrix of mitochondria
Identify three pieces of evidence for endosymbiotic theory by identifying three similarities between mitochondria and the ancestral species.
Mitochondria reproduce with binary fission like bacteria, double membrane, has its own DNA (circular like bacteria).
What is homeostasis?
Self-regulating process by which biological systems tend to maintain stable internal conditions (temperature, water/salt balance, pH, blood glucose, etc)
How are simple diffusion and facilitated diffusion different?
Simple diffusion moves without any help; Facilitated diffusion uses a membrane protein (carrier, ion channel, aquaporin, etc.) to help substance across the membrane.
How do small amounts of water pass through the membrane?
Small amounts of water can move by simple diffusion across cell membranes
What types of materials can easily pass through the membrane?
Small, nonpolar molecules can easily pass through the nonpolar fatty acid tail portion of the membrane example: oxygen and carbon dioxide
How does the structure of the smooth ER aid in the function?
Smooth ER is a network of membranes that separate the cell into compartments for metabolic processes. Smooth ER functions in the synthesis of lipids in most cells, the breakdown of toxins in liver cells, and storage and release of Ca ++ in muscle cells. Keeping the enzymes or molecules needed for a specific chemical pathway together in a specific area is more efficient.
What does it mean if a solution is isotonic?
Solute concentration in a solution is equal to the cell it surrounds
What composes the cell wall of a prokaryote?
peptidoglycan
What are the components of the cell membrane?
phospholipids, proteins, glycoproteins, glycolipids, cholesterol
What is embedded in the chloroplast and how does it aid in the function of the chloroplast?
photosystems containing chlorophyll to absorb sunlight
How do ions move across the membrane?
through ion channels
How is a concentration gradient established and maintained?
through molecular pumps and/or the movement of molecules across the membrane
