Course 8 Biology Unit 2 Cell Structure PDF

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Course 8 Biology Unit 2 Cell Structure. Answers to the whole homework(which are in green). Helps to complete the coursework when you don't have enough time to complete....

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Unit 2: Cell Structure and Function

TOPIC 2.1 Cell Structure: Subcellular Components ENDURING UNDERSTANDING SYI-1 Living systems are organized in a hierarchy of structural levels that interact. LEARNING OBJECTIVE SYI-1.D Describe the structure and/ or function of subcellular components and organelles. ESSENTIAL KNOWLEDGE SYI-1.D.1 Ribosomes comprise ribosomal RNA (rRNA) and protein. Ribosomes synthesize protein according to mRNA sequence.

Draw a detailed sketch of each organelle, label any important parts. Then sketch an object that reminds you of the FUNCTION of each cell part. Explain why the object reminds you of the function. (see Topic 2.2 for more about the functions of each organelle). Drawing

Object

Ribosomes

There are lots of possible answers for the objects chosen!

Explanation

Ribosomes are the location of protein synthesis (translation). RNA is read and the code used to form a polypeptide chain.

SYI-1.D.2 Ribosomes are found in all forms of life, reflecting the common ancestry of all known life. Smooth ER SYI-1.D.3 Endoplasmic reticulum (ER) occurs in two forms—smooth and rough. Rough ER is associated with membrane-bound ribosomes—

In charge of detoxification and formation of new phospholipids.

a. Rough ER compartmentalizes the cell. Rough ER

Studded with ribosomes, proteins are made here that are then transported to other parts of the cell. Rough ER also plays a role in intracellular transport.

Golgi Complex

Proteins come here to be modified and tagged to be sent to other parts of the cell, or to leave the cell.

b. Smooth ER functions include detoxification and lipid synthesis. X Specific functions of the smooth ER in specialized cells are beyond the scope of the AP Exam SYI-1.D.4 The Golgi complex is a membrane-bound structure that consists of a series of flattened membrane sacs—

a. Functions of the Golgi include the correct folding and chemical modification of newly synthesized proteins and packaging for protein trafficking. ILLUSTRATIVE EXAMPLE § Glycosylation and other chemical modifications of proteins that take place within the Golgi and determine protein function or targeting X The role of the Golgi in the synthesis of specific phospholipids and the packaging of specific enzymes for lysosomes, peroxisomes, and secretory vesicles are beyond the scope of the AP Exam.

Mitochondria

Lysosomes

Vacuole

b. Mitochondria have a double membrane. The outer membrane is smooth but the inner membrane is highly convoluted, forming folds c. Lysosomes are membrane-enclosed sacs that contain hydrolytic enzymes.

Chloroplast

d. A vacuole is a membrane-bound sac that plays many and differing roles. In plants, a specialized large vacuole serves multiple functions. e. Chloroplasts are specialized organelles that are found in photosynthetic algae and plants. Chloroplasts have a double outer membrane.

Location of Cellular Respiration, forming ATP that powers cellular processes.

Contain enzymes that break down faulty cell parts and invaders. Often described as the recycling centers of the cell.

Used for storage of water and other dissolved compounds needed by the cell. Large central vacuole in plants also used for support to hold up the cell wall. Site of Photosynthesis in autotrophs. Light energy is used to create glucose, converting radiant energy into chemical energy.

ribosomes, cell membrane Which cell part(s) are found in both Eukaryote and Prokaryote cells? ____________________ What does this suggest about the history of life?

The last universal common ancestor to all life likely had ribosomes and a cell membrane, which it then passed down to all of its descendants, eventually evolving into all domains of life.

Unit 2: Cell Structure and Function

TOPIC 2.2 Cell Structure and Function ENDURING UNDERSTANDING SYI-1 Living systems are organized in a hierarchy of structural levels that interact. LEARNING OBJECTIVE SYI-1.E Explain how subcellular components and organelles contribute to the function of the cell.

You are studying a cell and notice that Protein A is in the wrong location. What organelles may not be functioning properly? (there are two possibilities)

The golgi complex, or the Rough ER ESSENTIAL KNOWLEDGE SYI-1.E.1 Organelles and subcellular structures, and the interactions among them, support cellular function— a. Endoplasmic reticulum provides mechanical support, carries out protein synthesis on membrane-bound ribosomes, and plays a role in intracellular transport. b. Mitochondrial double membrane provides compartments for different metabolic reactions. c. Lysosomes contain hydrolytic enzymes, which are important in intracellular digestion, the recycling of a cell’s organic materials, and programmed cell death (apoptosis).

Predict what would happen if the lysosome membrane broke open. Explain your prediction.

Lysosomes are full of enzymes designed to break down cell parts, if these enzymes were not contained (spilled out into the cell) they could destroy the cell and kill it. Do you think cells would do this on purpose? They do! When? __________________ during controlled cell

death - apoptosis You have not watered your plant in a few days. It is droopy and floppy. What has happened on a cellular level (be specific to a particular organelle)? What will happen if you water it? Explain.

The central vacuole of the plant cells is designed to fill with water and push against cell walls, holding the plant upright. When dehydrated, the vacuoles shrink, and are no longer pushing against cell walls, so they sag, leading to drooping plants. When the plant is watered, vacuoles will fill again, push against ell walls, and the plant will stand upright again.

d. Vacuoles have many roles, including storage and release of macromolecules and cellular waste products. In plants, it aids in retention of water for turgor pressure.

Krebs Cycle The proteins involved in the ETC are embedded on the folded inner membrane On the Mitochondrion above, label the location of the Krebs Cycle and the location of the Electron Transport Chain.

LEARNING OBJECTIVE SYI-1.F Describe the structural features of a cell that allow organisms to capture, store, and use energy. ESSENTIAL KNOWLEDGE SYI-1.F.1 The folding of the inner membrane increases the surface area, which allows for more ATP to be synthesized.

Predict the symptoms of a person whose mitochondria have 50% less folding (less surface area) in their inner membrane. Explain your prediction.

The inner membrane holds enzymes involved in the Electron Transport Chain. The more membrane, the more surface area there is for ATP Synthase, which generates ATP. With less membrane, there would be fewer ATP Synthase, so less ATP production. This person would be very tired all of the time, having very little energy and not able to do physical activities - muscles require a large amount of ATP. They may also have trouble thinking or concentrating, nerve cells also use a lot of ATP.

SYI-1.F.2 Within the chloroplast are thylakoids and the stroma. SYI-1.F.3 The thylakoids are organized in stacks, called grana.

Stroma thylakoid disk

SYI-1.F.4 Membranes contain chlorophyll pigments and electron transport proteins that comprise the photosystems. SYI-1.F.5 The light-dependent reactions of photosynthesis occur in the grana. SYI-1.F.6 The stroma is the fluid within the inner chloroplast membrane and outside of the thylakoid. SYI-1.F.7 The carbon fixation (Calvin-Benson cycle) reactions of photosynthesis occur in the stroma. SYI-1.F.8 The Krebs cycle (citric acid cycle) reactions occur in the matrix of the mitochondria. SYI-1.F.9 Electron transport and ATP synthesis occur on the inner mitochondrial membrane

grana

Light Dependent Reaction Carbon Fixation (Calvin Cycle)

On the chloroplast, label the stroma, thylakoid disks, and grana. Label the location of the light dependant reactions and of Carbon Fixation.

Predict the result of doubling the number of thylakoids on glucose production in this chloroplast. Explain your prediction.

With twice the number of thylakoids, there would be double the surface area to conduct light dependent reactions. This would likely lead to an increase in glucose production (if the enzymes in the Calvin Cycle can keep up). Additional glucose would allow the plant to row faster (more cell wall material and more energy) provided that other requirements for growth are met (sufficient nitrogen and phosphorous available)

Unit 2: Cell Structure and Function

TOPIC 2.3 Cell Size ENDURING UNDERSTANDING ENE-1 The highly complex organization of living systems requires constant input of energy and the exchange of macromolecules. LEARNING OBJECTIVE ENE-1.B Explain the effect of surface area-to-volume ratios on the exchange of materials between cells or organisms and the environment. ESSENTIAL KNOWLEDGE ENE-1.B.1 Surface area-to-volume ratios affect the ability of a biological system to obtain necessary resources, eliminate waste products, acquire or dissipate thermal energy, and otherwise exchange chemicals and energy with the environment. **See formulas for surface area and volume in your Formula Sheet ENE-1.B.2 The surface area of the plasma membrane must be large enough to adequately exchange materials— a. These limitations can restrict cell size and shape. Smaller cells typically have a higher surface area-to-volume ratio and more efficient exchange of materials with the environment. b. As cells increase in volume, the relative surface area decreases and the demand for internal resources increases.

These two cylinders represent loaves of bread. With your pencil, draw lines to ‘cut’ the loaf on the right into slices.

Mentally drop each loaf into water. Which loaf will become saturated first? Explain why.

Cutting the loaf of bread into slices increases the surface area exposed to the water. The higher surface area to volume ratio of the sliced bread will cause it to become fully saturated sooner than the un-cut loaf. If the loaf were a living organism, why would it be better for that organism to be composed to many small pieces rather than one large piece?

Living organisms must be able to quickly take in substances from the environment (oxygen, water, nutrients) and get rid of waste (nitrogenous waste, carbon dioxide). The smaller the organism, the higher its surface area to volume ratio is, allowing it to preform transport into and out of the cell more quickly. Show your work! What is the surface area-to-volume ratio of... A cube shape cell, 3 cm x 3 cm

A sphere shape cell that has a 3 cm diameter

Surface area: 3 x 3 = 9 cm2 per side six sides = 54 cm2

Surface area = 4 (3.14) (1.5 x 1.5) = 28.3

Volume = 3 x 3 x 3 = 27 cm3

Volume = 4/3 (3.14) (3 x 3 x 3) = 14.1 cm3 SA to V ratio = 28.3 / 14.1 = 2.007

SA to V Ratio 54 / 27 = 2

Which cell is more efficient at eliminating waste and obtaining nutrients from its environment? How do you know? The sphere is just slightly more efficient- its surface area to volume

ratio is 0.007 greater than that of the cube.

c. More complex cellular structures (e.g., membrane folds) are necessary to adequately exchange materials with the environment.

Picture a hot potato. Now picture a GIANT HOT POTATO! Which potato will cool off faster? Why? Explain in terms of SA/V ratio.

d. As organisms increase in size, their surface area-to-volume ratio decreases, affecting properties like rate of heat exchange with the environment.

The hot potato is now a mouse, and the GIANT hot potato is now an elephant. Which organism must have a higher metabolic rate (burn more energy) to maintain its body heat? Explain why.

ILLUSTRATIVE EXAMPLES SA/V Ratios and Exchange § Root hair cells § Guard cells § Gut epithelial cells

LEARNING OBJECTIVE ENE-1.C Explain how specialized structures and strategies are used for the efficient exchange of molecules to the environment. ESSENTIAL KNOWLEDGE ENE-1.C.1 Organisms have evolved highly efficient strategies to obtain nutrients and eliminate wastes. Cells and organisms use specialized exchange surfaces to obtain and release molecules from or into the surrounding environment. ILLUSTRATIVE EXAMPLES § Vacuoles § Cilia § Stomata

The large potato would take a lot longer to cool off, as it has a smaller surface area to volume ratio. The best way to cool a hot potato is to open it up and cut it into pieces, increasing the surface area exposed to cool air. The elephant has a low SA to V ratio, so it holds onto heat, meaning it needs to spend less energy heating itself. The mouse, being small, has a high SA to V ratio and looses heat to the environment at a higher rate - so it must to burn more energy per unit mass in order to maintain its body temp - the mouse has a higher metabolic rate than the elephant Draw a root hair cell. Why is its shape important to its function?

The extended protrusion of the cell increases the SA to V ratio, allowing for faster material exchange uptake of water and minerals into the cell. Draw a very simple plant cell with a large central vacuole. How does a vacuole increase the rate that plant cells can exchange materials with its environment?

Vacuoles store food and nutrients, as well as wastes, winch can quickly diffuse into or out of the cytoplasm either to the environment, or do the vacuole.

Draw a gut epithelial cell. Why its shape important to its function?

Microvilli - extensions of the cell membrane increase the surface area, allowing for quicker absorption of nutrients from the small intestine to be absorbed into the blood stream. Draw a red blood cell. Why is the shape of the RBC important to its function?

RBCs are flattened, with an impression in the middle. This increases the surface area of the cell, allowing for more rapid absorption of oxygen into the cell, and release of oxygen as it moves though the body tissues.

Unit 2: Cell Structure and Function

TOPIC 2.4 Plasma Membranes ENDURING UNDERSTANDING ENE-2 Cells have membranes that allow them to establish and maintain internal environments that are different from their external environments. LEARNING OBJECTIVE ENE-2.A Describe the roles of each of the components of the cell membrane in maintaining the internal environment of the cell. ESSENTIAL KNOWLEDGE ENE-2.A.1 Phospholipids have both hydrophilic and hydrophobic regions. The hydrophilic phosphate regions of the phospholipids are oriented toward the aqueous external or internal environments, while the hydrophobic fatty acid regions face each other within the interior of the membrane. ENE-2.A.2 Embedded proteins can be hydrophilic, with charged and polar side groups, or hydrophobic, with nonpolar side groups.

LEARNING OBJECTIVE ENE-2.B Describe the Fluid Mosaic Model of cell membranes. ESSENTIAL KNOWLEDGE ENE-2.B.1 Cell membranes consist of a structural framework of phospholipid molecules that is embedded with proteins, steroids (such as cholesterol in eukaryotes), glycoproteins, and glycolipids that can flow around the surface of the cell within the membrane.

Hydrophobic Label the hydrophobic and hydrophilic parts of one phospholipid. There are three proteins embedded in the membrane. Choose a color for hydrophobic R groups ⬜ and hydrophilic R groups.⬜ Color code the regions of each protein. Predict what would happen if a mutation caused one of the hydrophobic R groups to be switched with a hydrophilic R group. Explain your thoughts:

The hydrophobic R groups are anchoring the protein in the phospholipid membrane, as it is water-free between the membrane layers. If those R Groups were hydrophilic, the protein would fall out of the membrane and could no longer perform its function.

Hydrophylic

Hydrophobic R Groups would embed in the hydrophobic region between phospholipd lipid layers, while the hydrophilic R groups would be stinking out, of the membrane, exposed to water.

Choose one lipid to make into a glycolipid, and one protein to make into a glycoprotein by adding a chain of glucose molecules to it.

The fluid mosaic model states that the parts of the cell membrane continually move past one another. If the diagram above where a photo of a living cell membrane, draw a representation of that same cell if you took another photo 20 minutes later. Add the same three proteins to the diagram on the left.

Any drawing with the proteins in different positions (though same orientation to the membrane itself) - showing that the proteins have moved.

Unit 2: Cell Structure and Function

TOPIC 2.5 Membrane Permeability ENDURING UNDERSTANDING ENE-2 Cells have membranes that allow them to establish and maintain internal environments that are different from their external environments. LEARNING OBJECTIVE ENE-2.C Explain how the structure of biological membranes influences selective permeability. ESSENTIAL KNOWLEDGE ENE-2.C.1 The structure of cell membranes results in selective permeability. ENE-2.C.2 Cell membranes separate the internal environment of the cell from the external environment. ENE-2.C.3 Selective permeability is a direct consequence of membrane structure, as described by the fluid mosaic model. ENE-2.C.4 Small nonpolar molecules, including N2, O2, and CO2 , freely pass across the membrane. Hydrophilic substances, such as large polar molecules and ions, move across the membrane through embedded channel and transport proteins. ENE-2.C.5 Polar uncharged molecules, including H2O, pass through the membrane in small amounts.

LEARNING OBJECTIVE ENE-2.D Describe the role of the cell wall in maintaining cell structure and function. ESSENTIAL KNOWLEDGE ENE-2.D.1 Cell walls provide a structural boundary, as well as a permeability barrier for some substances to the internal environments. ENE-2.D.2 Cell walls of plants, prokaryotes, and fungi are composed of complex carbohydrates.

What is selective permeability?

The cell has properties that allow it to allow only some molecules to pass across the membrane, allowing it to help maintain homeostasis within the cell. How does the Fluid Mosaic nature of the cell membrane impact its ability to allow some small molecules pass through freely?

As phospholipis are flowing around, small non-polar molecules are able to diffuse though the membrane more easily. A rigid cell membrane would be less permeable to these molecules. What property of the phospholipid bilayer prevents the movement of small polar molecules across the membrane?

The hydrophobic portion of the bilayer prevents polar (hydrophilic) molecules from being able to come across the membrane. What kinds of cells have cell walls (three types), and what type of carbohydrate material is each cell wall made of?

Plant cell walls are made of cellulose

Fungus cell walls are made of chitin.

Bacterial cell walls are made of peptidoglycan.

Name two functions of the cell wall:

Cell walls provide structural support for the cell. They also prevent the cell from taking on too much water via osmosis, providing pressure against the inflow of water, so that the cell does not burst in hypotonic environments.

Unit 2: Cell Structure and Function

TOPIC 2.6 Membrane Transport ENDURING UNDERSTANDING ENE-2 Cells have membranes that allow them to establish and maintain internal environments that are different from their external environments. LEARNING OBJECTIVE ENE-2.E Describe the me...