IB Biology HL - Unit 3: Cellular Biology
Compare and contrast how Paramecium and Chlamydomonas carry out the functions of life.
Paramecium: - Asexual reproduction - Vacuoles for digestion, powers growth - Excretion through cell membrane Chlamydomonas: - Asexual and sexual reproduction - Photosynthesis or consuming other organisms for growth - Excretion through cell membrane
Electron microscopes have a much (lower/higher) resolution than light microscopes.
higher
Diameter (HP) =
(Diameter (LP) x magnification of LP objective) / magnification of HP objective
A cell is 2000x larger than life size, and the image is measured to be about 5.8 cm. Determine the actual size of the cell.
29 µm
What is the function of mitochondria and where can they be found?
Mitochondria use glucose and oxygen to convert food into energy, in the form of ATP. They can be found in eukaryotic cells.
The capacity of stem cells to divide and differentiate along different pathways is necessary in ___ and also makes stem cells suitable for therapeutic uses
embryonic development
What cell organelle is visible? (Flip to see picture) - mitochondria - vacuole - chloroplast - golgi apparatus
golgi apparatus
During endocytosis, what change will most likely occur in the plasma membrane of a cell? - It will form vesicles. - It will become electrically charged. - It will partially dissolve. - It will form two phospholipid monolayers.
It will form vesicles.
A paramecium is shown at about 800X life size, and the image is measured to be about 3.6 cm. Determine the actual size of the cell.
45 µm
The erythrocytes below were imaged using an electron microscope. The magnification is x3000 and the ruler measures the central cell as being 2 cm (20mm) in diameter. (Image not included) Estimate the actual size of this erythrocyte. - 60 µm - 0.6µm - 6.6 µm - 6000µm
6.6 µm
The image shows an electron micrograph of mesophyll cells. (Flip to see picture) What is the name of the structure labelled X? A) Cytoplasm B) Mitochondrion C) Nucleus D) Chloroplast
D) Chloroplast
Cells in the adrenal gland produce the hormone epinephrine and store it in vesicles. To release epinephrine these vesicles are carried to the plasma membrane and fuse with it. What process is occurring? A) Expulsion B) Exchange C) Excretion D) Exocytosis
D) Exocytosis
Which structure is found in E. coli, but not in a eukaryotic cell? A) Cell wall B) Endoplasmic reticulum C) Cytoplasm D) Pili
D) Pili
Which of the following is not a component of eukaryotic cell membranes? - Short-chain RNAs - Phospholipid bilayer - Cholesterol molecules - Carbohydrates
Short-chain RNAs
Particles move across membranes by which six processes?
Simple diffusion, facilitated diffusion, osmosis, active transport, endocytosis, and exocytosis.
Phospholipids form ___ in water due to the ___ properties of phospholipid molecules.
bilayers, amphipathic
Prokaryotic cells divide using ___.
binary fission
Specialized tissues can develop by ___.
cell differentiation in multicellular organisms
Surface area to volume ratio is important in the limitation of ___.
cell size
Which structure is not a component of all cells? - cell wall - ribosomes - cell membrane - genetic material
cell wall
According to the cell theory, living organisms are composed of ___.
cells
What cell organelle is visible? (Flip to see picture) - vacuole - chloroplast - golgi - ER
chloroplast
Eukaryotes have a (compartmentalized/non compartmentalized) cell structure.
compartmentalized
The fluidity of membranes allows materials to be taken into cells by ___ or released by ___. Vesicles move materials within cells.
endocytosis, exocytosis
Multicellular organisms have properties that emerge from ___.
the interaction of their cellular components
cm to mm
x 10
A cell is 80 µm in length. If drawn 600 times actual size, how long will the drawing be in mm? - 0.13mm - 48mm - 48µm - 12.5mm
48mm
What is the rate of metabolism?
A function of its mass/volume.
Organisms consisting of one cell carry out ___ in that cell.
all functions of life
What is the rate of material exchange?
A function of its surface area.
Prokaryotic and eukaryotic cells have many differences, but they also share some common features. Which of the following may be found in either type of cell? - mitochondria - ribosomes - nucleus - golgi body
ribosomes
mm to cm
/ 10
Explain how the process of facilitated diffusion occurs and describe a specific example for the process.
- Allows larger particles such as ions to pass through - Particles pass through protein channels - Protein channels have proteins on the inside - Protein channels only allow one type of particle to pass through - Protein channels change shape due to the carrier proteins - Substances move from high to low concentration - Substances move down a concentration gradient Ex: Glucose for skeletal muscle
Describe how each of the following types of experimental evidence contributed to the falsification of the Davson-Danielli model: - Freeze-etched electron micrograph - Structure of membrane proteins - Fluorescent antibody tagging
- Freeze-etched electron micrograph: When rapidly freezing and fracturing cells, transmembrane proteins were apparent in the micrographs. - Structure of membrane protein: Scientists extracted proteins, which they found to vary in size and could not form continuous layers on the periphery of the membrane. They also found that the tails of the phospholipids are also hydrophobic, so they point inward and face each other. - Fluorescent antibody tagging: This process involved tagging antibodies that bind to membrane proteins and tracking them. Scientists found that the tags were mixed, indicating that membrane proteins are free to move within the membrane rather than being fixed.
What are examples of exocytosis?
- Pancreas into liver, glucagon - T cells into viral infected cells, protein-filled vesicles
What are examples of endocytosis?
- Placenta, proteins and antibodies - White blood cells, pathogens - Lysosomes, wastes - Amoeba, food
Describe the Singer-Nicolson model (also known as the fluid mosaic model).
- Proteins are inserted into the lipid bilayer - The cell membrane is mainly composed of three macromolecules: phospholipids, cholesterol, and proteins - Two types of proteins in a membrane: integral and peripheral proteins - Integral proteins are imbedded in the phospholipid bilayer - Peripheral proteins are attached to the inner or outer suface of the membrane
Explain how the process of simple diffusion occurs and describe a specific example for the process.
- Substance moves between phospholipids - Particles can only pass through if the phospholipid bilayer is permeable to them - Substances move from high to low concentration - Substances move down a concentration gradient - Substances move until a state of equilibrium is reached - Does not require energy or help from proteins Example: Water, oxygen, and carbon dioxide molecules passing through
Explain the pathway that enzymes (which are proteins) synthesized by the rough endoplasmic reticulum will take through the cell to be secreted. - How will they move throughout the cell? - What organelle(s) will they go to and in what order? - What happens to them at each organelle? - How are they eventually secreted?
- The proteins are packaged into transport vesicles, which move to the next destination - 1) rough endoplasmic reticulum + ribosomes 2) golgi complex 3) plasma membrane - 1) translated by ribosomes and packaged into transport vesicles 2) vesicles fused to unload proteins into golgi complex, modified and packaged into secretory vesicle - They are eventually secreted by exocytosis, where the secretory vesicle fuses with the plasma membrane and the particles are released.
Discuss how striated muscle could be considered an exception to the cell theory.
- They are 100X longer than regular cells (30mm) - They contain many nuclei, sometimes even several hundred
Discuss how aseptate fungal hyphae could be considered an exception to the cell theory.
- They are not divided up into sections (cells) - They contain many nuclei - They are very large - They have a continuous cytoplasm
Discuss how giant algae could be considered an exception to the cell theory.
- They can grow very large (up to 100mm) - They are composed of only one cell with one nucleus
Explain how the process of osmosis occurs and describe a specific example for the process.
- Water moves due to a net movement of molecules - When the concentration of solutes is larger on one side, the amount of water is higher on that side - Net movement of water from regions of lower solute concentration to regions of higher solute concentration - Water moves through channels called aquaporins Example: Kidney cells reabsorbing water and root hair cells absorbing water from soil
µm to mm
/ 1000
µm to cm
/ 10000
A red blood cell is 8 μm in diameter. If drawn 100 times larger than its actual size, what diameter will the drawing be in mm?
0.8mm
A student determines that the field of view with a 10x ocular and a 4x objective is 2.5 mm in diameter. What is the diameter with the same ocular and a 10x objective?
1 mm
Describe the process of binary fission.
1) Circular DNA and plasmids replicate, however plasmids may replicate more than once - both copies of DNA attach to the plasma membrane 2) Plasma membrane begins to grow between the two DNA molecules and the cytoplasm begins to divide 3) Cytoplasm divides to produce two daughter cells, each with a single copy of the circular DNA and a variable number of plasmids
Identify and briefly describe the seven functions of life.
1) Metabolism, a process that converts food to energy 2) Response to stimuli, a reaction to the environment and threats 3) Nutrition, food 4) Growth, an increase in size, a change in shape, etc. 5) Excretion, a release of waste 6) Homeostasis, a balance between organic functions 7) Reproduction, the production of offspring (asexual or sexual)
State the three principles of the cell theory.
1. All organisms are composed of one or more cells. 2. Cells are the smallest units of life. 3. All cells come from preexisting cells.
If an amoeba is being viewed with a low power microscope with a 4.5 mm field of view, what is the estimated longest length of the organism? Show your work. (The amoeba is about 1/3 of the FOV)
1.5 mm
A cell is observed using a CHS microscope under high power and is estimated to be about half the 0.5mm field of view. A student then draws the cell 25 cm in length. What is the magnification of the drawing? - 800X - 2000X - 4X - 1000X
1000X
If a mitochondrion has a length of 5 µm and a student's drawing of the mitochondrion is 10 mm, what is the magnification of the drawing?
2000x
A student, observing a microorganism under a magnification of 40X, estimates that it is about 100 micrometers long. If she then draws the microorganism 2 cm long, what is the magnification of her drawing? - 0.5X - 200X - 100X - 400X
200X
This micrograph of a liver cell is 2500X larger than life size and depicted 60mm in diameter. How many micrometers is the actual length of the diameter of this cell? - 50µm - 24µm - 15µm - 42µm
24µm
The following information is for a microscope which has an eyepiece lens (ocular lens) with a power of 10X. Using the information provided, calculate the field diameter for high power. Objective Lens: Objective Power: FOV Diameter: Low 4X 3500µm Medium 10X High 40X - 3500X - 1400X - 350X - 140X
350X
The diameter of one DRAWING of a cell is 33mm. The diameter of the cell in REAL LIFE is estimated to be 60 micrometers. The cell is viewed under 400X magnification. What is the drawing magnification? In other words, how many times larger is the drawing than an actual cell? - 0.5X - 2X - 500X - 600X
600X
A student draws a cell diagram 24mm long, which is 400X larger than life size. How many micrometers is the actual cell? - 60µm - 0.06µm - 0.6µm - 6µm
60µm
What is essential for diffusion? - A source of energy - A concentration gradient - A selectively permeable membrane - Proteins
A concentration gradient
In osmosis, a solvent moves from: - The outside of a cell to the inside. - A low concentration of solute to a high concentration of solute. - A high concentration of solute to a low concentration of solute. - The inside of a cell to the outside.
A low concentration of solute to a high concentration of solute.
Which of the following best describes an integral protein? - A protein enclosed in a vesicle - A protein attached to the surface of the membrane - A protein embedded in the phospholipid membrane - A protein within the cytoplasm
A protein embedded in the phospholipid membrane.
Which process is possible due to the fluidity of cell membranes? A) Endocytosis B) Osmosis C) ATP production D) Cell recognition
A) Endocytosis
What happens to the surface area to volume ratio as a cell grows? A) It decreases B) It increases C) It doubles D) It does not change
A) It decreases
What provides evidence for the endosymbiotic theory? A) Mitochondrial DNA in eukaryotic cells B) 70S ribosomes in prokaryotic cells C) Gene transfer from prokaryotic cells to eukaryotic cells using plasmids D) Prokaryotic cells (Escherichia coli) in the large intestine digest proteins
A) Mitochondrial DNA in eukaryotic cells
What are the characteristics of eukaryotic cells? A) Nucleus: present, Mitochondria: present, Ribosomes: 80S B) Nucleus: present, Mitochondria: absent, Ribosomes: 70S C) Nucleus: absent, Mitochondria: present, Ribosomes: 80S D) Nucleus: absent, Mitochondria: absent, Ribosomes: 70S
A) Nucleus: present, Mitochondria: present, Ribosomes: 80S
What is osmosis? A) The movement of water through a membrane from a low to a high solute concentration B) The movement of solutes through a membrane from a high to a low water concentration C) The movement of water through a membrane from a high to a low solute concentration D) The movement of solutes through a membrane from a low to a high water concentration
A) The movement of water through a membrane from a low to a high solute concentration
When muscle cells form cardiac muscle tissue in the heart they can pump blood. If you only ever studied individual cardiac muscle cells you would never see the blood pumping properties. What is this type of property called? - An integral property - A peripheral property. - An emergent property. - A powerful property.
An emergent property.
State as many differences as you can between animal and plant cells.
Animal cells: - Multiple small vacuoles - Lysosomes - Centriole - Cholesterol in plasma membrane Plant cells: - Large central vacuole - Chloroplasts - Cell wall
A single stem cell can form a range of different daughter cells. Which of the statements best describes how this happens? - Mitosis causes stem cells to multiply and change. - Using cell apoptosis cells change. - By controlling the expression of genes stem cells differentiate. - By condensation reactions cells join together forming tissue.
By controlling the expression of genes stem cells differentiate.
Which statement is part of the cell theory? A) Cells are composed of organic molecules B) Cells have DNA as their genetic material C) Cells have a cytoplasm surrounded by a membrane D) Cells come from preexisting cells
D) Cells come from preexisting cells
What is the function of the plant cell wall? A) Formation of vesicles for transport of large molecules B) Prevention of excessive water uptake C) Communication with other cells by means of glycoproteins D) Active transport of ions
B) Prevention of excessive water uptake
What route is used to export proteins from the cell? A) Golgi apparatus → rough endoplasmic reticulum → plasma membrane B) Rough endoplasmic reticulum → Golgi apparatus → plasma membrane C) Golgi apparatus → lysosome → rough endoplasmic reticulum D) Rough endoplasmic reticulum → lysosome → Golgi apparatus
B) Rough endoplasmic reticulum → Golgi apparatus → plasma membrane
Which feature of striated muscle cells allows them to be considered as a possible exception to the cell theory? A) They are found in multicellular organisms B) They contain more than one nucleus C) They are specialized for movement D) They do not carry out mitosis
B) They contain more than one nucleus
How do multicellular organisms differentiate? A) Some cell types divide by mitosis more often than others B) They express some of their genes but not others C) Some of their proteins denature but not others D) Their DNA content changes with time
B) They express some of their genes but not others
What distinguishes prokaryotic cells and eukaryotic cells? (Flip to see table)
B) cell structure not compartmentalized, cell structure compartmentalized
Which graph represents the change in surface area to volume ratio with increasing cell diameter? (Flip to see picture)
B
Which of the following correctly describes exocytosis? - A: Plasma membrane increases in size: No, Plasma membrane is pulled inwards: Yes, Membranes fuse: No, Vesicles move away from the plasma membrane: Yes - B: Plasma membrane increases in size: Yes, Plasma membrane is pulled inwards: No, Membranes fuse: Yes, Vesicles move away from the plasma membrane: No - C: Plasma membrane increases in size: No, Plasma membrane is pulled inwards: Yes, Membranes fuse: Yes, Vesicles move away from the plasma membrane: Yes - D: Plasma membrane increases in size: No, Plasma membrane is pulled inwards: No, Membranes fuse: No, Vesicles move away from the plasma membrane: Yes
B
The image represents an Escherichia coli. What is the function of structure X? (Flip to see picture) A) Active transport B) Attachment C) Binary fission D) Cell respiration
B) Attachment
Which features are present in prokaryotic cells? A) DNA, plasma membrane and mitochondria B) DNA, cell wall and pili C) Ribosomes, chloroplasts and cell wall D) Cytoplasm, ribosomes and rough endoplasmic reticulum
B) DNA, cell wall and pili
Which process requires channel proteins? A) Simple diffusion B) Facilitated diffusion C) Binding of hormones D) Exocytosis
B) Facilitated diffusion
What is a role of cholesterol in animal cells? A) It increases body fat B) It controls membrane fluidity C) It lines the inner wall of capillaries D) It is a constituent of bile
B) It controls membrane fluidity
What is a function of the plant cell wall? A) Formation of vesicles for transport of large molecules B) Prevention of excessive water uptake C) Communication with other cells by means of glycoproteins D) Active transport of ions
B) Prevention of excessive water uptake
The statement relates to Pasteur's experiments. "In his experiments, Louis Pasteur demonstrated that: - if broth was boiled to kill all organisms and was then kept in swan-necked flasks, preventing the entry of organisms, no organisms grew in the broth - if the swan-necked flask was broken, mold soon started to grow in the broth. What did this statement suggest? A) Mold evolved by endosymbiosis B) Oxygen is required for anaerobic respiration C) Cells can only be formed by division of pre-existing cells D) Nutrients are a requirement for mold growth
C) Cells can only be formed by division of pre-existing cells
Which of the following will contribute to the cell theory? I. Living organisms are composed of cells. II. All cells come from pre-existing cells by mitosis. III. Cells are the smallest units of life. A) I only B) II only C) I and III only D) I, II, and III
C) I and III only
What is the function of the Golgi apparatus? A) Transport of lipids B) Synthesis of polypeptides C) Processing of proteins for secretion D) Generation of most of the cell's supply of ATP
C) Processing of proteins for secretion
Which functions of life are carried out by all unicellular organisms? A) Response, homeostasis, growth and photosynthesis B) Metabolism, ventilation, reproduction and nutrition C) Response, homeostasis, metabolism and growth D) Reproduction, ventilation, response and nutrition
C) Response, homeostasis, metabolism and growth
Which organelle is involved in generating vesicles destined for the cell membrane? A) Golgi apparatus B) Smooth endoplasmic reticulum C) Rough endoplasmic reticulum D) Lysosome
C) Rough endoplasmic reticulum
What do diffusion and osmosis have in common? A) They only happen in living cells B) They require transport proteins in the membrane C) They are passive transport mechanisms D) Net movement of substances is against the concentration gradient
C) They are passive transport mechanisms
What are the functions of glycoproteins and glycolipids.
Cell organism recognition (which is important for fighting pathogens) and signaling.
Describe the limits to cell size. Why can't cells grow indefinitely?
Cell size is limited by its surface area to volume ratio. The metabolism of the cell, which takes place in the cytoplasm, is proportional to the volume of the cell. The surface area represents the membrane around the outside of the cell, known as the plasma membrane, which moves materials into and out of the cell. As cells get larger, their surface area to volume ratio decreases. It is more efficient for a cell to copy and divide than to grow very large, so when cells get too large, they just divide.
The 'Cell theory' states that all living things are made of cells. Which of the statements below also form part of the 'cell theory'? - Cells come from pre-existing cells. - Cells are surrounded by a cell wall. - Cells contain proteins. - Cells have a nucleus.
Cells come from pre-existing cells.
What is the function of microtubules and centrioles and where can they be found?
Centrioles and microtubules function in regulating cell growth and movement as well as key signaling events. Microtubules can be found in eukaryotic cells and centrioles can be found in animal cells.
In what organelle does the food making process in plants take place? - Mitochondria - Endoplasmic Reticulum - Vacuole - Chloroplasts
Chloroplasts
What is the function of chloroplasts and where can they be found?
Chloroplasts convert water and carbon dioxide (powered by sunlight) into glucose, which can be used for cellular respiration. They can be found in plant cells.
What is the function of the plasma membrane in a prokaryotic cell? - Hosts small protein structures that synthesize proteins by translating messenger RNA. - Is a region of the cytoplasm that contains naked DNA, which is the genetic information of the cell. - Controls entry and exit of substances, pumping some of them in active transport. - Forms a protective outer layer that prevents damage from outside and also bursting, if internal pressure is high.
Controls entry and exit of substances, pumping some of them in active transport.
What structures are part of an Escherichia coli cell? A) Ribosomes, nucleoid and Golgi apparatus B) Ribosomes, mitochondria and pili C) Cell wall, plasma membrane and nuclear membrane D) Pili, flagella and cytoplasm
D) Pili, flagella and cytoplasm
A botanist measures a leaf and finds it is 24 cm long and 8 cm wide. His drawing of the leaf is 4 cm wide. Which was the magnification and length of his drawing, assuming that the proportions of the drawing were correct? A) Scale: X2, Length/cm: 48 B) Scale: X2, Length/cm: 12 C) Scale: X0.5, Length/cm: 48 D) Scale: X0.5, Length/cm: 12
D) Scale: X0.5, Length/cm: 12
What is the difference between simple diffusion and facilitated diffusion? A) Simple diffusion: Rate decreases with increasing concentration gradient, Facilitated diffusion: Rate increases with increasing concentration gradient B) Simple diffusion: Faster movement of molecules, Facilitated diffusion: Slower movement of molecules C) Simple diffusion: Always involves a membrane, Facilitated diffusion: Never involves a membrane D) Simple diffusion: Uses any part of a membrane, Facilitated diffusion: Uses channels in the membrane
D) Simple diffusion: Uses any part of a membrane, Facilitated diffusion: Uses channels in the membrane
Which property makes stem cells suitable for therapeutic use? A) They can divide by meiosis to form gametes B) They contain chemicals that can kill bacteria C) Their chromosomes are suitable for gene transfer and cloning D) They can differentiate into specialized cells
D) They can differentiate into specialized cells
Why do multicellular organisms have emergent properties? A) They have more genes than unicellular organisms B) Properties of unicellular organisms are enhanced by having many cells C) All of their genes are expressed whereas unicellular organisms express only some D) They show properties that can only result from the interaction of many cells
D) They show properties that can only result from the interaction of many cells
Describe the role that stem cells play in embryonic development and therapy.
Embryonic stem cells can be used to replace damaged cells that result from injury or disease. This is done with in vitro growth stimulated by hormone therapy. Adult stem cells can also be used for numerous transplants, such as bone marrow. Stem cells play a major role in embryonic development, as they are capable of dividing many times to produce large amounts of tissue during the early stages, where a sperm fertilizes an egg cell to produce a zygote, which forms an enzyme.
Distinguish between embryonic and adult stem cells. Include their source(s), therapeutic advantages and therapeutic disadvantages.
Embryonic stem cells: - From an embryo - Undifferentiated and can become any type of cell - Not difficult to obtain, but there are moral objections - Almost unlimited growth potential - Somewhat high risk of developing a tumor - Low risk of genetic damage - Removal of cells from the embryo kills it Adult stem cells: - From certain adult tissues - Partially differentiated and can become a limited number of cells - Difficult to obtain - Limited growth potential - Low risk of developing a tumor - Removal of cells does not kill the adult
Define emergent properties. How does this relate to multicellular organisms?
Emergent properties are characteristics that result from the interactions of specialized cells in multicellular organisms. Specialized cells can work together, meaning that multicellular organisms can carry out more functions of life than the sum of each individual cell.
Compare and contrast the processes of endocytosis and exocytosis.
Endocytosis: - Moves particles from outside to inside - Forms new vesicles from the membrane - Internal vesicles are formed - Intake of particles - Vesicle is added Both: - Active transport - Involves vesicles containing particles - Requires ATP to form vesicles - Large amount of molecules transported - Controlled by golgi complex Exocytosis: - Moves particles from inside to outside - Fusion of vesicles with the membrane - Secretory vesicles are formed - Removal of waste products - Vesicle disappears - Contents are released outside the cell
Which statements are characteristics of diffusion through membranes? I. Polysaccharides (large molecules) can be transported. II. Diffusion can be facilitated by special channels. III. Diffusion is affected by concentration gradients. - I, II, and III - II and III only - I and II only - I and III only
II and III only
Compare the ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord of a new baby and from an adult's own tissues.
Ethics of stem cells from specially created embryos: - Embryos must die in order for the cells to be extracted (often viewed as taking a human life) - Almost unlimited growth potential - Ability to differentiate into any type of cell in the body - Higher risk of developing a tumor - Lower risk of receiving genetic damage - Higher chance of being genetically different from the patient Ethics of stem cells from the umbilical cord of a new baby: - Nothing dies in order for the cells to be extracted - Easily obtained and stored - Storage services already available - Fully compatible with the tissues of the adult - Limited differentiation capacity - Limited quantities of stem cells from one baby's cord - The cord us discarded whether the stem cells are taken from it or not Ethics of stem cells from an adult's own tissues: - Nothing dies in order for the cells to be extracted - Difficult to obtain - Limited growth potential - Smaller chance of developing a tumor - Limited differentiation capacity - Fully compatible with the tissues of the adult
List and describe the functions of the organelles present in exocrine gland cells of the pancreas and palisade mesophyll cells of a leaf.
Exocrine gland cells of the pancreas: - Plasma Membrane: Gland cells excrete substances through it - Nucleus: DNA to provide mRNA - Endoplasmic Reticulum: Creates enzymes (proteins) which are transported outside the cell - Ribosomes: Create emzymes (proteins) - Lysosomes: Break down food and other particles - Golgi Apparatus: Processes proteins - Mitochondria: Cellular respiration - Centrosome: Organize microtubules - Vacuoles: Transport materials Palisade mesophyll cells of a leaf: - Cell wall: holds shape of cell wall and protects it - Plasma membrane: Cells excrete substances through it - Nucleus: DNA to provide mRNA - Ribosomes: Create enzymes (proteins) - Mitochondria: Cellular respiration - Chloroplasts: Photosynthesis - Vacuoles: transport materials and water storage
The action of a membrane allowing substances to move between it through channel proteins is known as: - Facilitated diffusion - Diffusion - Cohesion - Osmosis
Facilitated diffusion
What is the function of a flagella and pili on an Escherichia coli?
Flagella: Allow mobility Pili: Perform DNA transfer and attachment to surfaces
Create a table to outline the functions of the following parts of the cell membrane: phospholipids, cholesterol, integral proteins and peripheral proteins.
Function, Phospholipids: Self assemble to form flexible bilayers, protect cell against accumulation of fats, help lipids move, assist nucleus. Function, Cholesterol: Reduces fluidity and permeability to some solutes, prevents phospholipid solidification, helps form vesicles. Function, Integral protein: Receptor; transports large molecules and energy signals. Function, Peripheral protein: Receptor; allows cells to coordinate and communicate using networks of proteins.
What substance in the cell membrane serves the purpose of cell recognition? - Cholesterol - Hydrophilic heads - Integral protein - Glycoprotein
Glycoprotein
Define pluripotent.
Having the ability to differentiate into many cell types.
Which of the following is not a function of proteins associated with cell membranes? - Hormone Receptors - Heredity - Catalysis - Transport
Heredity
Explain what would happen to a red blood cell placed in hypertonic, hypotonic and isotonic solutions and why.
Hypertonic: They would shrink and shrivel up because hypertonic solutions have a higher concentration of solutes, meaning there are more solutes outside the cell, which causes the water to exit the cell. Hypotonic: They would swell and rupture because hypotonic solutions have a lower concentration of solutes, meaning there are less solutes outside the cell, which causes the water to enter the cell. Isotonic: This is an ideal solution because the cells will not shrink or expand in it due to the fact that the concentrations of solutes on either side are in equilibrium, so water enters and exits the cell, allowing it to maintain its shape.
Distinguish between the uses and applications of light microscopes and electron microscopes. What can data of each microscope provide?
Light microscopes are used to observe specimens with a size of as low as 0.2µm, as the size and magnification is limited by the speed of light (400-700nm). If lenses that are over 400X magnification are used, the images typically appear blurry. Although light microscopes can provide detailed images of micro aspects of specimens and are relatively inexpensive, they are extremely limited by the speed of light. However, electron microscopes are able to zoom in farther and provide a clear image, as beams of electrons have a much shorter wavelength. The resolution of most electron microscopes is 0.001µm. Light microscopes reveal the structure of cells while electron microscopes reveal the ultrastructure.
What organelle helps with cell digestion? - ER - Ribosomes - Golgi Complex - Lysosomes
Lysosomes
What is the function of lysosomes and where can they be found?
Lysosomes break down waste products such as macromolecules, respond to viruses, and help repair the cell membrane. They can be found in eukaryotic cells.
Write the equation for calculating the magnification of drawings and the actual size of structures in drawings or micrographs.
Magnification = Size of Image / Actual Size of Specimen.
What organelle is called the "powerhouse" of a cell? - Nucleolus - Nucleus - Mitochondria - Endoplasmic Reticulum
Mitochondria
Are viruses living?
No, they do not carry out all of the life functions. They must use cells to reproduce.
Explain how to measure the size of an object using a light microscope.
One can measure the size of an object using a light microscope by determining the size of the image of the object (mm) and the magnification of the image. The actual size of the specimen is discovered by dividing the size of the image by the magnification.
Which definition corresponds to osmosis? - Active transport of water molecules from a region of lower solute concentration to a region of higher solute concentration. - Passive movement of water molecules from a region of lower solute concentration to a region of higher solute concentration. - Passive movement of water molecules from a region of higher solute concentration to a region of lower solute concentration. - Passive movement of particles from a region of higher concentration to a region of lower concentration.
Passive movement of water molecules from a region of lower solute concentration to a region of higher solute concentration.
Compare passive and active transport.
Passive transport: - Does not require energy - Moves down (along) a concentration gradient (high to low) Both: - Aid substances in the movement into a cell - Help eliminate waste - Have a concentration gradient Active transport: - Requires energy (in the form of ATP) - Moves up (against) a concentration gradient (low to high)
What is the function of cilia, pili, and flagella and where can they be found?
Pili are used to transfer DNA and for attachment to surfaces. Flagella are used to move an entire cell. Cilia are used to move entire cells or substances along the outer surface of the cell. Cilia can be found in eukaryotic cells, pili can be found in prokaryotic cells, and flagella can be found in all cells.
Describe the structure and function of a potassium channel for facilitated diffusion in an axon of a nerve cell. What does it look like and how does it work?
Potassium channels regulate the movement of potassium ions as they travel through membranes. Before potassium ions can pass through these channels, they must break their bonds with the surrounding water molecules. Once they are through the pores, they can once again have a shell of water molecules. These channels can only fit potassium. In axons, these channels are gated, and open and close depending on the amount of positive and negative charges across the membrane.
Distinguish between the structure of prokaryotic and eukaryotic cells. How are they different?
Prokaryotic: - No nucleus - No membrane-bound organelles - Small (1-10 microns) - DNA closed loop in cytoplasm - 70S ribosomes - Nucleoid region - Fimbrae, cell wall, flagella Both: - Cytoplasm - Ribosomes - DNA - Plasma membrane Eukaryotic: - Nucleus - Membrane-bound organelles - Large (10-100 microns) - DNA Double Helix in nuclear envelopes - 80S ribosomes - Nucleus - Mitochondria, lysosomes
There are seven processes which are said to be possessed by all living things. This venus fly trap has just caught an unfortunate fly. The fly is trying to escape from the trap. Which characteristic of living things, shared by both plants and insects, is illustrated by the action in this photo? - Reproduction. - Growth. - Response to the environment. - Excretion.
Response to the environment.
What is the function of ribosomes and where can they be found?
Ribosomes read the messenger RNA (mRNA) sequence and translate it into a specified string of amino acids, which grow into long chains that fold to form proteins. They are the site of protein synthesis in the cell. Ribosomes can be found in all cells.
Describe the structure and function of a sodium-potassium pump for active transport in an axon of a nerve cell. What does it look like and how does it work?
Sodium-potassium pumps are used when axons need to convey messages from one part of the body to another in an electrical form that is called a nerve impulse. This nerve impulse uses a rapid movement of sodium and then potassium ions across the axon membrane.
Describe how stem cells are used to treat Stargardt's disease and leukemia.
Stargardt's Disease (Macular Degeneration) is a result of the inheritance of two recessive genes that cause retinal cells in the eye to not be able to process vitamin A properly. Scientists use stem cells to treat this disease by taking embryonic stem cells and directing them to develop into retinal cells which are then placed in the eye of the person suffering from the disease. These retinal cells remain in the eye. Leukemia is a type of cancer. In order to cure leukemia, the cancer cells in the bone marrow that are producing excessive numbers of white blood cells must be destroyed. Chemicals must be exposed to patients in order to kill dividing cells through chemotherapy. Stem cells play the role of producing blood cells to fight the disease, but since stem cells are killed in radiation, they are extracted and reinserted into the patient.
Some people say that the cell theory isn't a good theory because there are exceptions. Which of the following could be considered an exception to cell theory? - The theory of spontaneous generation has been disproved. - Acetabularia algae are made from cells without a nucleus. - Striated muscles are made from elongated cells with multiple nuclei. - Many plants contain Xylem vessels which are dead.
Striated muscles are made from elongated cells with multiple nuclei.
What is the function of nucleus? - Structure that contains DNA and directs the cell - Membrane that surrounds and protects the cell - Stack of membranes that packages chemicals - Structure that organizes motion of chromosomes.
Structure that contains DNA and directs the cell
What is the function of the mitochondria? - Structure that converts nutrients to energy - Stack of membranes that packages chemicals - Structure that contains DNA and directs the cell - Structure that manufactures ribosomes
Structure that converts nutrients to energy
Which ratio is thought to limit the size of cells? - Surface area to volume ratio. - DNA to cytoplasm volume ratio. - DNA to RNA ratio. - Respiration to oxygen ratio.
Surface area to volume ratio.
Describe the Davson-Danielli model. What evidence did they have that led to their proposed model?
The Davson-Danielli model was proposed in 1935 and it stated that the plasma membrane has a sandwich model in which the phospholipid bilayer is surrounded by proteins on each end. This model was proposed in order to emphasize that membranes are extremely effective barriers, and it derived from the invention of high magnification electron micrographs, which showed membranes with a railroad track appearance where proteins are dark and phospholipids are light.
What is the function of the cell membrane and where can it be found?
The cell membrane regulates the transport of materials entering and exiting the cell. It can be found in all cells.
What is the function of the cell wall and where can it be found?
The cell wall forms a framework for the cell to prevent over expansion. It can be found in prokaryotic cells and plant cells.
What is the function of the golgi apparatus and where can it be found?
The golgi apparatus is a place where proteins synthesized by the rough endoplasmic reticulum are further processed and sorted for transport to their eventual destinations: lysosomes, the plasma membrane, or secretion. It can be found in eukaryotic cells.
Which of the following statements about phospholipids is correct? - Both the heads and the tails are hydrophilic. - The heads are hydrophilic and the tails are hydrophobic. - Both the heads and the tails are hydrophobic. - The heads are hydrophobic and the tails are hydrophilic.
The heads are hydrophilic and the tails are hydrophobic.
What is the function of the nucleus and where can it be found?
The nucleus controls and regulates the activities of the cell and stores the cell's DNA. It can be found in all eukaryotic cells.
Which of the following statements about the cell membrane is false? - The outer part of the membranes is hydrophobic. - Specific substances are moved across the membrane through active pump. - Cholesterol within the membrane helps maintain its structure. - Enzymatic reactions may happen in the membrane.
The outer part of the membranes is hydrophobic.
What is facilitated diffusion? - The passive movement of a particle across a cell membrane via a channel protein. - The movement of a particle up a concentration gradient helped by active pumping. - The movement of a particle down a concentration gradient helped by active pumping. - The passive movement of a particle through the phospholipid bilayer of the cell membrane.
The passive movement of a particle across a cell membrane via a channel protein.
What is diffusion? - The property of cells in multicellular organisms to develop in different ways, allowing them to carry out different functions. - The passive movement of particles from a region of higher concentration to a region of lower concentration; it results in a random motion of particles. - The passive movement of water molecules from a lower solute concentration to a region of higher solute concentration across a partially permeable membrane. - The capacity to self-renew by cell division.
The passive movement of particles from a region of higher concentration to a region of lower concentration; it results in a random motion of particles.
What is osmosis? - The passive movement of particles from a region of higher concentration to a region of lower concentration and results in a random motion of particles. - The passive movement of water molecules from a lower solute concentration to a region of higher solute concentration across a partially permeable membrane. - The capacity to self-renew by cell division. - The property of cells in multicellular organisms to develop in different ways, allowing them to carry out different functions.
The passive movement of water molecules from a lower solute concentration to a region of higher solute concentration across a partially permeable membrane.
Explain how specialized tissues can develop by cell differentiation. What is meant when we say a gene is "expressed"? What role does gene expression play in cell differentiation?
The process of cell differentiation involves a cluster of identical cells being exposed to hormones, which causes the hormones to reach certain parts of the cluster of cells. These hormones cause some genes to be expressed, meaning that the gene is turned on and it produces proteins. Some genes are turned on, while others are turned off, creating differentiated cells, which causes specialized tissues. Gene expression is the key element of cell differentiation because it is what causes the cells to differentiate, by turning some genes on and others off.
Explain the importance of the surface area to volume ratio as a factor limiting cell size.
The rate of metabolism of a cell is a function of its volume. The rate of material exchange in and out of a cell is a function of its surface area. As the cell grows, volume increases faster than surface area. If the metabolic rate is greater than the rate of exchange of vital materials and wastes, the cell will eventually die. Hence the cell must consequently divide in order to restore a viable SA:Vol ratio and survive.
What is the function of the rough endoplasmic reticulum and where can it be found?
The rough endoplasmic reticulum, which contains many attached ribosomes, has the role of synthesizing proteins. It can be found in eukaryotic cells.
What is the function of the smooth endoplasmic reticulum and where can it be found?
The smooth endoplasmic reticulum is responsible for the synthesis of essential lipids such as phospholipids and cholesterol. It is found in most eukaryotic cells.
Explain why the structure of phospholipid molecules causes them to form bilayers in water.
The structure of phospholipid molecules causes them to form bilayers in water because the heads are attracted to the water, while the tails are not, so they face each other, forming a double layer.
Explain how the structure of the phospholipid molecule gives it amphipathic properties.
The structure of the phospholipid molecule gives it amphipathic properties because the head (the phosphate group) is polar and hydrophilic, meaning it dissolves in water, while the tails (the hydrocarbon chains) are nonpolar and hydrophobic, so they hide from the water and form a bilayer. When a molecule has both hydrophilic and hydrophobic parts, it is considered amphipathic.
Which of the following are special properties of stem cells which make them so useful for new medical treatments? - They are large and difficult to damage. - They can make antibodies to protect against disease. - They can divide, and differentiate along different (divergent) pathways. - They are very small and can be frozen to preserve them.
They can divide, and differentiate along different (divergent) pathways.
What is the function of active transport? - To construct the cell wall by synthesizing cellulose fibers in vesicles and adding them to the inner surface of the cell wall. - To divide the nucleus in order to form two genetically identical nuclei. - To move substances against the concentration gradient, from a region of lower concentration to a region of higher concentration. - To carry out many biochemical reactions and grow the cell.
To move substances against the concentration gradient, from a region of lower concentration to a region of higher concentration.
What are the five general functions of proteins?
Transport: Protein channels (facilitated) and protein pumps (active). Receptors: Peptide-based hormones (insulin, glucagon, etc.). Anchorage: Cytoskeleton attachments and extracellular matrix. Cell recognition: Major histocompatibility complex proteins and antigens. Intercellular joinings: Tight junctions and plasmodesmata. Enzymatic activity: Metabolic pathways (eg electron transport chain).
What is the function of vacuoles and vesicles and where can they be found?
Vacuoles and vesicles are membrane-bound sacs that function in storage and transport. They can be found in all cells, although they are much more uncommon in animal cells.
Cholesterol is a component of ___ cell membranes
animal
Eukaryotic cells multiply sexually through ___.
meiosis
Eukaryotic cells multiply asexually through ___.
mitosis
Total magnification =
objective lens x ocular lens
The cell membrane is a ______________ bilayer of ____________ . - semi-permeable / phospholipids - permeable / proteins - permeable / phospholipids - semi-permeable / proteins
semi-permeable / phospholipids
Prokaryotes have a ___ cell structure (with/without) compartmentalization.
simple, without
Differentiation involves the expression of ___ in a cell's genome.
some genes and not others
An E. coli cell has four organelles labelled. A) Nucleoid B) Flagella C) Ribosome D) Pili What is the function of A? - movement through watery environment - stick to host cells - store genetic instructions - store genes for antibiotic resistance
store genetic instructions
mm to µm
x 1000
cm to µm
x 10000
The electron microscope image below shows a scale bar marked with 10µm. It has been measured to be 3.5cm (i.e. 35 mm) long by a student using the rule shown. (Image not included) What is the magnification of the image? - x3500 - x330 - x3300 - x350
x3500