BIO UNIT 2: The Cell

Describe the structure of the nucleus. (2 points)

* Conspicuous membrane-bound cellullar organelle in EU cells. * Contains most of the genes that control the entire cell.

Explain the chart for protein synthesis in the cytoplasm.

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Explain the importance of compartmentalization in mitochondrial function.

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What is a ribosome?

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1. What is mitochondria? (2 points) 2. The number of mitochondria per cell varies and directly correlates to _______.

1. *Organelles that are cites of cellular respiration and production of ATP. (This is a catabolic oxygen-requiring process that uses energy extracted from organic macromolecules to produce ATP. ) * They move, change shape, and divide. 2. the cell's metabolic activity. 3.

1. What is a nucleus? 2. It contains most of the _____ that control the entire cell. 3. It's primary functions are:

1. A conspicuous membrane-bound cellular organelle in a eukaryotic cell. 2. genes 3. Storage, transmission, and expression of genetic information used to synthesize proteins that determine the structure and function of the cell.

1. What is a nuclear envelope? 2. Describe it. (3 points)

1. A double membrane which encloses the nucleus in a eukaryotic cell. 2. * It is 2 lipid bilayer membranes separated by a space of about 20 - 40 nm. * Each lipid bilayer has its own specific proteins. * It is perforated by pores.

What is the structure of a mitochondrion?

1. Enclosed by 2 membranes that have their own combination of proteins embedded in phospholipid bilayers. 2. Smooth outer membrane is highly permeable to small solutes, but blocks proteins & other macromolecules. 3. Inner membrane contains embedded enzymes that are involved in cellular respiration. The membrane's many infoldings (cristae) increase the surface area for those reactions to occur. 4. The inner and outer membranes divide the mitochondrion into two internal compartments: (a) Intermembrane space & (b) Mitochondrial matrix

What is the structure and function of the endoplasmic reticulum? What is the difference between rough and smooth ER?

1. Extensive membranous network of tubules and sacs (AKA cisternae) which sequesters its internal lumen (cisternal space) from the cytosol. 2. The most extensive portion of the endomembrane system. 3. Continuous w/ the outer membrane of the nuclear envelope; ∴ the space between the membranes of the nuclear envelope is continuous with cisternal space. 4. Two distinct regions: Smooth and Rough. The difference is that smooth is not studded with ribosomes and rough is.

1. Explain the function of a eukaryotic ribosome. 2. Distinguish between free and bound ribosomes? 3. Cells specializing in protein secretion, often have more __________ ribosomes. 4. Cells with high rates of protein synthesis have prominent ______ & many ________.

1. It is a cytoplasmic organelle that is the site for protein (polypeptide) synthesis. It creates proteins from all amino acids and RNA representing the protein. 2. Free: Most proteins made by free ribosomes will function in the cytosol for that cell's use. Bound: Most proteins are destined for membrane inclusion or export. 3. bound. (i.e. pancreatic cells) 4. Nucleoli and ribosomes. (i.e. human liver cell has a few million)

Explain the structure of a eukaryotic ribosome. (4 points)

1. It is a cytoplasmic organelle that is the site for protein synthesis. 2. They are constructed in the nucleolus. 3. The are complexes of RNA and protein. *** DNA is used to make RNA, which is used to make protein. 4. They function freely in the cytosol or bound to endoplasmic reticulum (ER). In either case, they are are STRUCTURALLY identical and interchangeable.

1. Describe pore complex. 2. The nucleus contains most of the cell's DNA which is organized with proteins into a complex called ______.

1. It regulares molecular traffic in and out of the nucleus. 2. chromatin.

What are chromosomes? (3 points)

1. Long threadlike association of genes, composed of chromatin and found in the nucleus of eukaryotic cells. 2. Each species has a characteristic chromosome # 3. Human cells have 46 chromosomes, except egg and sperm cells which have half (23)

1. What are lysosomes? 2. What do they do? (3 points)

1. Membrane bound organelles that contain acid hydrolytic enzymes involved in digestion. 2. * Fluid in lysomsomes is highly acidic and ∴ they act as "cellular stomachs," breaking down bacteria and debris that get into the cell. * Break down damaged cell organelles * Participate in the immune system

1. What are the components of the endomembrane system? (6 points) (Nine Elephants Graze in Large Vacant Plains) 2. What does ER mean?

1. Nuclear envelope 2. Endoplasmic reticulum 3. Golgi apparatus 4. Lysosomes 5. Vacuoles 6. Plasma membrane (not actually an endomembrane, but related to the system) 2. Endoplasmic = within the cytoplasm Reticulum = network

1. The most visible structure within the non-dividing nucleus is the ________. 2. Describe it. 3. _____ is transcribed and assembled within the nucleolus. 4. It is the RNA component of the ________ and the _______ manufacturing machinery of all living cells.

1. Nucleolus. 2. It is a non-membrane bound structure composed of proteins and nucleic acids found within the nucleus. 3. Ribosomal ribonucleic Acid (rRNA) 4. ribosome. protein.

1. What is cytoplasm? What does it contain?

1. Organelles and cytosol. It is the region that makes up the interior of the cell except the nucleus. 2. It contains the organelles (except nucleus) and ________???????? (fluid)

Distinguish between the following "areas" for both prokaryotic and eukaryotic cells: 1. What organisms they exist in? 2. Their cell size? 3. Their metabolism?

1. PRO: Bacteria & Cyanobacteria. EU: Protozoa, fungi, plants, and animals 2. PRO: 1-10 μm. EU: 5-100 μm 3. PRO: Anaerobic or aerobic. EU: Aerobic

Distinguish between the following "areas" for both prokaryotic and eukaryotic cells: 1. What organelles exist in them? 2. What kind of DNA do they have? 3. How are RNA and protein synthesized?

1. PRO: Few or none. No true nucleus; lacks a nuclear envelope. EU: Nucleus, mitochondria, etc. 2. PRO: Circular DNA in cytoplasm. EU: Linear DNA with non-coding regions and bound by nuclear envelope. 3. PRO: Synthesized in same compartment EU: RNA synthesized and processed in nucleus. Proteins synthesized in cytoplasm.

Distinguish between the following "areas" for both prokaryotic and eukaryotic cells: 1. What goes on in the cytoplasm? 2. How do cells divide? 3. How are cells organized?

1. PRO: No cytoskeleton, cytoplasmic streaming, endocytosis, or exocytosis. EU: Cytoskeleton with protein filaments, cytoplasmic streaming, endocytosis, and exocytosis 2. PRO: Chromosomes pulled apart by attachments to plasma membrane. EU: Chromosomes pulled apart by cytoskeletal spindle apparatus. 3. PRO: Mainly unicellular. EU: Mainly multicellular, with differentiation of many cell types.

Explain the 4 functions of the smooth ER.

1. Participate in synthesis of lipids, phospholipids, and steroids. 2. Participates in carbohydrate metabolism. 3. Detoxifies drugs and poisons. 3. Stores calcium ions necessary for muscle contraction.

What are peroxisomes and what is their role in eukaryotic cells? (3 points)

1. Peroxisomes are membrane-bound vesicles containing oxidative enzymes that use oxygen to strip hydrogen from specific molecules and to produce H₂O₂. 2. Catalase then decomposes H₂O₂ (toxic to cells) into harmless H₂O and O₂. 3. In the liver and kidney cells, peroxisomes use H₂O₂ to detoxify various ingested molecules.

1. Describe the structure and function of the extracellular matrix in animal cells. 2. What are two main classes of extracellular macromolecules?

1. Structure: Extracellular space made up of proteins and polysaccharides. Function: Support, adhesion, movement, and development of cells. 2. Polysaccharide chains and fibrous proteins (i.e. collagen)

1. What are the three classifications of cell junctions?

1. Tight, adhesive, and gap.

What is cytoplasmic streaming & what does it do? (2 points)

1. When the cytoplasm of the cells move by following actin filaments. 2. It transports nutrients, enzymes, and larger particles within cells and enhances the exchange of materials between organelles and between cells.

The nucleus controls protein synthesis in the cytoplasm. Fill in the blanks for this flow. 1. Messenger RNA (mRNA) _________ in the nucleus from ____ instructions. --> 2. Passes through ________ into _________. --> 3. Attaches to ____________ where the genetic message is translated into _______________.

1. transcribed. DNA. 2. nucleus pores. cytoplasm. 3. ribosomes. primary protein structure.

What is a chromatid?

A chromatid is one of the two identical copies of DNA making up a duplicated chromosome, which are joined at their centromeres. *** Once separated into two, they are referred to as chromosomes again. Chromosomal components from image: (1) Chromatid (2) Centromere (3) Short arm (4) Long arm

What is chromatin?

A complex of DNA and histone proteins, which makes up chromosomes in eukaryotic cells. It appears as a mass of stained material in non-living cells.

What does ampipathic mean?

A molecule containing both polar (water-soluble) and non-polar (not water-soluble) portions in its structure. OR a molecule having hydrophobic and hydrophilic regions.

What are microvilli and pseudopodia?

Cells that are specialized for absorption (ex: intestinal cells) have folds in the plasma membrane called microvilli that increase the surface area. Pseudopodia are temporary extensions of the plasma membrane used for movement or to engulf particles.

Why is compartmentalization important in eukaryotic cells?

Compartmentalization is important because a cell's compartments provide different local environments that accomodate specific metabolic processes. This allows for incompatible process to go on simultaneously inside the same cell.

Explain in greater detail how the smooth ER detoxifies drugs and poisons.

Contains many enzymes in the liver that catalyzes the addition of OH groups. This makes them more soluble in the cytosol so they can be excreted from the body.

What are cilia and flagella?

Hairlike structures projecting from the cell that function to move the cell by their movements. Cilia are shorter, but are similar in construction. I.e. Sperm uses flagella to move.

Explain in greater details how the smooth ER stores calcium ions necessary for muscle contraction.

In a muscle cell, the ER membrane pumps Ca⁺⁺ from the cytosol into the cisternal space. The Ca⁺⁺ then leaks from the ER back into the cytosol, which triggers muscle contraction.

What is the plasma membrane?

It covers the cell surface.

Explain the function of the rough ER.

It manufactures secretory proteins for export or lysosomes???

Describe the function of the nucleus.

It's like the brain of the cell: Storage, transmission, and expression of genetic information used to synthesize proteins that determine the structure and function of the cell.

How does impaired lysosomal function cause the symptoms of inherited storage diseases? Give 2 examples.

Lack of specific lysosomal enzymes causes substrate accumulation which interferes with lysosomal metabolism and other cellular functions. Examples: Pompe's disease: missing enzyme is carbohydrase that breaks down glycogen. This causes liver damage. Tay-Sach's disease: Lyposomal lipase is missing. It causes lipid accumulation in the brain

Describe the structure of Adhesive Junctions (Desmosomes) and relate their structure to function.

Structure: Thickened patched in the cell membrane region between two cells. They contain specialized proteins. Function: Button-like junctions that mechanically attach cells to their neighbours or to the extracellular matrix. They hold adjacent cells firmly together that are susceptible to considerable stretching. *** Do not form a complete seal.

What are organelles and where are they located?

Small compartments, like rooms in a house - inside the cell. They are located in the cytosol.

Explain in greater detail how the smooth ER participates in carbohydrate metabolism.

Smooth ER in the liver contains an embedded enzyme that catalyzes the final step in the conversion of glycogen to glucose (it removes phosphate from glucose-phosphate).

Give examples of where the smooth ER participates in synthesis of lipids, phospholipids, and steroids.

Steroids secreted by adrenal gland. Generally, cells that produce and secrete these products are rich in smooth ER (i.e. testes, ovaries, skin oil glands)

What are the main differences between prokaryotic & eukaryotic cells? Explain in more detail.

Structural organization & Volume Structural organization: EU cells have: * Compartments * Unique lipid and protein compositions * Participate in metabolic rxns * Provide localized environmental conditions & sequester rxns so they can occur w/out interference Volume: The average EU cell has 1000 x the volume & 100x the surface area of a PRO cell.

Describe the structure (3 points) and function of microtubules.

Structure: 1. Small cylindrical fibres that change in length by assembling (polymerizing) & disassembling (depolymerizing). 2. Made of protein called tubulin. 3. Controlled by an area near the nucleus called the centrosome (microtubule organizing area). Function: 1. Act as tracks along which organelles can move. 2. Responsible for movement of cilia and flagella. 3. Move chromosomes during cell division.

Describe the structure (1) and function (5) of microfilaments (AKA actin filaments).

Structure: Long thin fibres composed of 2 chains of protein wrapped around each other. Function: 1. Bundles or meshlike networks which provide mechanical support and determine the shape of the cell. 2. Assist in the movement of almost all EU cells. 3. Important for muscle contraction. 4. During cell division a ring of microfilaments that surround the cell constricts, pinching the cell in two. 5.Cytoplasmic streaming

Describe the structure and function (4) of intermediate filaments.

Structure: Long, thread-like protein molecules wrapped around one another like the strands of a cable. ***They are intermediate in size when compared to microfilaments (smallest) and microtubules (largest). Function: 1. Maintain cell's shape. 2. Mechanical support for the cell and organelles. 3. Prevent excessive stretching. 4. Attach cells together (adhesive junction)

Describe the structure of Tight Junctions and relate their structure to function.

Structure: Membranes join together at cell to cell junctions. Function: Prevents fluids from leaking between adjacent cells.

Describe the structure of Gap Junctions and relate their structure to function.

Structure: Two cells separated by a small gap, which is bridges by channels that allow passage of water and small molecules. Function: They help to coordinate the activities of adjacent cells.

How does the nucleus control protein synthesis in the cytoplasm

The nucleus controls protein synthesis in the cytoplasm by (1) Messenger RNA (mRNA) is transcribed in the nucleus from DNA instructions. --> (2) It then passes through nucleus pores into cytoplasm. --> (3) Finally, it attaches to ribosomes where the genetic message is translated into primary protein structure. T

Explain the (a) intermembrane (IM) space & (b) the mitochondrial matrix (MM) of the mitochondrion.

a) IM Space: Narrow region between inner and outer mitochondrial membranes. Reflects the solute composition of the cytosol, b/c the outer membrane is permeable to small solute molecules. b) MM: Compartment enclosed by inner mitochondrial membrane. Contains enzymes that catalyze many many steps of cellular respiration, some of which are embedded in the inner membrane.