Chapter 4 Study Guide
Describe the structures and functions of the four compartments of eukaryotic cells.
1.The nuclear compartment comprising the nucleus 2.The intercisternal space which comprises the space between the membranes of the endoplasmic reticulum (which is continuous with the nuclear envelope) 3.Organelles 4.The cytosol Compartments have three main roles. One is to establish physical boundaries for biological processes that enables the cell to carry out different metabolic activities at the same time. This may include keeping certain biomolecules within a region, or keeping other molecules outside. Within the membrane-bound compartments, different intracellular pH, different enzyme systems, and other differences are isolated. With mitochondria, the cytosol has an oxidizing environment which converts NADH to NAD+. With these cases, the compartmentalization is physical. Another is to generate a specific micro-environment to spatially or temporally regulate a biological process. As an example, a yeast vacuole is normally acidified by proton transporters on the membrane. A third role is to establish specific locations or cellular addresses for which processes should occur. For example a transcription factor may be directed to a nucleus, where it can promote transcription of certain genes.
Relate the structures of plant cell walls and plasmodesmata to their functions.
4.21 Cell walls enclose and support plant cells 1. A plant cell, but not an animal cell, has a rigid cell wall that a. protects and provides skeletal support that helps keep the plant upright against gravity and b. is primarily composed of cellulose. 2. Plant cells have cell junctions called plasmodesmata that serve in communication between cells.
Describe the functions of ribosomes. Explain why some ribosomes are free in the fluid of the cytoplasm while others are bound to the endoplasmic reticulum or nuclear envelope.
B. 4.6 Ribosomes make proteins for use in the cell and export 1. Ribosomes are involved in the cell's protein synthesis. a. Ribosomes are synthesized from rRNA produced in the nucleolus. b. Cells that must synthesize large amounts of protein have a large number of ribosomes. 2. Some ribosomes are free ribosomes; others are bound. a. Free ribosomes are i. suspended in the cytoplasm and ii. typically involved in making proteins that function within the cytoplasm. b. Bound ribosomes are i. attached to the endoplasmic reticulum (ER) associated with the nuclear envelope and ii. associated with proteins packed in certain organelles or exported from the cell.
Compare the structures and functions of microfilaments, intermediate filaments, and microtubules.
Diameter: Microfilaments < intermediate filament < microtubule Microfilaments (actin filaments) are made up of actin monomers strung together into strands and then coiled together. Polar. Use ATP to form. Intermediate filaments are composed of many strands of fibrous subunits twisted together. They function to provide structural support for cell (tensile strength, resist force before failure—stretching), anchor the nucleus, provide an adaptable connection between the cell membrane and the cytoskeleton and maintain the nuclear envelope. Much more stable than actin or microtubules...distribute tensile strength across cells and tissues. Microtubules are made up of alpha and beta tubulin monomers that assemble as rings onto the + end of the tube and depolymerize at the (-) end of the tube. Polar. Use GTP to form. Tubulin dimers polymerize end to end to form protofilaments. (+) end subunits add more rapidly, subject to dynamic instability (beta subunits exposed). At the (-) end, anchored in MTOC (centrosome) and regulated by it (alpha subunits exposed).
Describe the four functional categories of organelles in eukaryotic cells.
Eukaryotic organelles comprise four functional categories: -manufacture (synthesis of macromolecules and transport within the cell), -breakdown (elimination and recycling of cellular materials - energy processing (conversion of energy from one form to another) -support, movement, and communication (maintenance of cell shape, anchorage, and movement of organelles, and relationships with extracellular environments) All four categories work together as an integrated team, producing the emergent properties at the cellular level.
Describe the structure and functions of the nucleus. Explain how DNA is packaged inside of the nucleus.
Nucleus: Structure: it contains 1 nuclear envelope ( gateway to the nucleus) 2 Chromosomes ( genetic containers) 3 nucleolus ( pre assembly point for ribosomes) Function:it directs the chemical reactions in cells by transcribing genetic information from DNA into RNA. nucleus also stores genetic information & transfers it during cell division from one cell to the next.it Controls cell's genetic program & metabolic activities. The DNA is put in chromosomes that stay in the nucleus and stay in there for when the cell reproduces and splits into 2 sister cells.
Distinguish between the structures of prokaryotic and eukaryotic cells.
Prokaryotic (meaning "before nucleus") have no nucleus and have no membrane bound organelles (i.e. mitochondria, chloroplast, endoplasmic reticulum, etc.). All bacteria are prokaryotic. All prokaryotes are bacteria. Eukaryotic (meaning "true nucleus") cells have genetic information contained within a nucleus and have membrane bound organelles.
Describe the structure of a plasma membrane and relate these parts to the functions of the plasma membrane.
The plasma membrane consists of both lipids and proteins. The fundamental structure of the membrane is the phospholipid bilayer, which forms a stable barrier between two aqueous compartments. In the case of the plasma membrane, these compartments are the inside and the outside of the cell. Proteins embedded within the phospholipid bilayer carry out the specific functions of the plasma membrane, including selective transport of molecules and cell-cell recognition.
Compare the structures and functions of chloroplasts and mitochondria.
The structures of these two organelles are easily recognizable. They both have two membranes, and the inside of the chloroplast also has stacks of membrane disks that are individually called thylakoids and collectively called grana. The functions of these two organelles are fundamental opposites: 1. The chloroplast builds glucose in order to store energy for the cell. It uses carbon dioxide and water and releases oxygen during this process of photosynthesis. 2. The mitochondrion breaks glucose down in order to get the energy out to make ATP. ATP is what the cells use directly for energy for any cell processes. The process uses glucose and oxygen and releases carbon dioxide and water during cellular respiration.
Describe the two parts of cell theory.
Well there are three. 1. All living organisms are made up of one or more cells. 2. Cells are the basic unit of organization in an organism. 3. All cells come from other cells.
Compare the structures of plant and animal cells. Note the function of each cell part.
http://www.diffen.com/difference/Animal_Cell_vs_Plant_Cell
Describe the structures and functions of the components of the endomembrane system, including smooth and rough endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes.
http://www2.swccd.edu/~mseteachingresources/msetrshare/biology/bakhiet/BIO100/Study%20Guide%20Ch%204.pdf 4.7-4.12
