Chapter 3 Learning Outcomes - Cellular Level of Organization Flashcards
3.1 Describe the cell theory and the process of cellular differentiation. p. 95
Cell theory:
- Cells are the building blocks of all plants and animals
- All new cells come from the division of pre-existing cells
- Cells are the smallest living units that carry out all vital functions
Cellular differentiation is a process of gradual specialization of cells during which daughter cells begin to develop specialized structural and functional characteristics to that form the tissues of the body (epithelial, connective, muscle, nervous)
3.2 Describe the cell and its organelles, including the structure and function of each. p. 96
Cells consist of:
- plasma membrane - separates cytoplasm from interstitial/extracellular fluid
- cytoplasm - material between the the plasma membrane and the membrane around the nucleus (cytosol + organelles)
- cytosol - intracellular fluid
- organelles - intracellular structures within the cytosol that perform specific functions (membranous or non-membranous)
Nonmembranous Organelles:
- cytoskeleton, microvilli, centrioles, cilia, flagelle, ribosomes
Membranous Organelles:
- mitochondria, nucleus, endoplasmic reticulum, golgi apparatus, lysosomes, peroxisomes
- Mitochondria structure = double membrane, with inner membrane folds enclosing important metabolic enzymes function = produces 95% of the ATP required by the cell
- Nucleus structure - a fluid nucleoplasm containing enzymes, proteins, DNA, and nucleotides; surrounded by a double membrane, the nuclear envelope function - controls metabolism, stores and processes genetic information, controls protein synthesis
- Endoplasmic reticulum structure = network of membranous sheets and channels extending throughout the cytoplasm function - synthesis of secretory products; intracellular storage and transport; detoxification of drugs or toxins 1. Smooth ER, which has no attached ribosomes, synthesizes lipids and carbohydrates 2. Rough ER, which has ribosomes bound to the membranes, modifies and packages newly synthesized proteins
- Golgi apparatus structure = stacks of flattened membranes (cisternae) containing chambers function = stores, alters, and packages synthesized products
- Lysosomes structure = vesicles (membranous sacs) containing digestive (oxidative) enzymes function = breakdown of organic compounds and damaged organelles or pathogens
- Peroxizomes structure = vesicles (membranous sacs) containing degradative enzymes function = breakdown of organic compounds; neutralization of toxic compounds generated in this process
3.3 Describe the structural and functional features of the plasma membrane. p. 98
The plasma membrane is a selectively permeable barrier that separates the inside of the cell from the surrounding extracellular fluid.
It’s a thin and delicate phospholipid bilayer, with each half-layer consisting of a hydrophilic head at the surface and a hydrophobic tail at the middle.
Structural features include:
- integral (transmembrane) proteins - SOME contain pores and channels through which waters and solutes may pass. Integral proteins greatly outnumber peripheral proteins.
- peripheral proteins - bound to the inner or outer layer of the plasma membrane; may have regulatory or enzymatic functions. (Easily separated from the surface, like sticky notes)
- glycocalyx - a layer of superficial membrane carbohydrates that is important in cell recognition, binding to extracellular structures, and lubrication of the cell surface
- cholesterol - stiffens the plasma membrane to make it less fluid and permeable; an important component of plasma membranes; almost one cholesterol molecule for each phospholipid molecule.
3.4 Differentiate among the structures and functions of the cytoskeleton. p. 100
Microfilaments, intermediate filaments provide cell shape
microtubules provide cell shape and move organelles
Centrioles - cylindrical structures composed of short microtubules
Function: organize microtubules in the spindle to move chromosomes during cell division
Cilia - propel fluids or solids across a cell surface
Flagella - propels sperm
3.5 Describe the ribosome and smooth and rough endoplasmic reticula, and indicate their specific functions. p. 102
Ribosomes are where proteins are synthesized. Some live on rough ER (fixed ribosomes) and some float around in the cell.
Rough ER is where newly synthesized proteins are chemically modified and packaged in transport vehicles to be delivered to the Golgi apparatus.
Smooth ER has tubular cisternae and synthesizes lipids, hormones, and glycogen.
this is the answer for the LO on pg 101... 3 types of fibers: Microfilaments Intermediate filaments Microtubules
Centriole - 9 groups of microtubule TRIPLETS form a short cylinder
Cilia - 9 groups of microtubule DOUBLETS form a cylinder (motile or primary)
Flagella - same microtubule structure as motile cilia but are longer and beat in a wavelike fashion (sperm)
3.6 Describe the Golgi apparatus, and indicate its specific functions. p. 104
The Golgi apparatus is a packaging center.
Proteins synthesized in the rough ER are delivered by transport vehicles to the CIS face of the Golgi’s cisternae (cis - receiving/”on this side”). Cisternae migrate to the TRANS side of the Golgi and then used for membrane renewal, secretion, or enzymes for cytosol. Transport vehicles are returned to the cis face for reuse.
3.7 Describe the structure of a mitochondrion, and explain the significance of mitochondria to cellular function. p. 106
Mitochondria are the powerhouse of the cell and produce ATP.
Structure: Double membrane, with inner folds enclosing important metabolic enzymes.
Function: produces 95% of the ATP required by the cell
3.8 Describe the role of the nucleus in maintaining homeostasis at the cellular level. p. 109
When the extracellular environment changes, the cell has mechanisms that can provide short-term feedback. If environmental stresses persist, the cell must adapt, which requires long-term changes to its characteristics. These adjustments are made in the nucleus.
3.9 Describe the functions of the cell nucleus, and distinguish between chromatin and a chromosome. p. 110
The nucleus contains DNA, RNA, organizing proteins, and enzymes.
Chromatin are DNA strands in cells that are not dividing; loosely coiled piles
At the beginning of cell division, DNA coiling becomes tighter and more complex and forms distinct structures called chromosomes.
3.10 Discuss the nature of the genetic code, and summarize the process of protein synthesis. p. 112
Genetic code is the “language” the cell uses.
DNA = AT, CG RNA = AU, CG
Summary of protein synthesis:
1. DNA triplets determine the sequence on mRNA codons
(transcription encodes genetic information onto a strand of RNA)
2. mRNA codons determine the sequence of tRNAs
(translation builds polypeptides)
3. the sequence of tRNAs determines the sequence of amino acids in the protein or polypeptide.
3.11 Summarize the process of transcription. p. 114
Transcription encodes genetic instructions on a strand of RNA.
- histone “unzips” the 2 DNA strands, and the DNA triplets determine the sequence of mRNA codons
Occurs in the nucleus (as opposed to translation, which occurs in the cytoplasm)
3.12 Summarize the process of translation. p. 116
Translation builds polypeptides as directed by an mRNA strand.
Anticodons on tRNA bind to codons on mRNA. Each type of tRNA carries a specific type of amino acid.
- One of the steps in protein synthesis, after transcription.
- Occurs in the ribosome. (protein factory)
3.13 Contrast permeable, selectively permeable, and impermeable membranes. p. 119
All living cells have selectively permeable membranes, meaning that they only permit the passage of some materials.
Permeable membranes allow any substance to pass through, impermeable membranes don’t allow anything through. NO LIVING CELLS have a permeable OR an impermeable membrane.
3.14 Explain the process of diffusion, and identify its significance in the body. p. 120
Diffusion = passive movement of ions and molecules, driven by concentration differences (passive transport)
Diffusion is necessary for the movement of water, dissolved solutes, nutrients, and waste products in and out of cells ACTIVE AND PASSIVE TRANSPORT ARE REQUIRED TO MAINTAIN HOMEOSTASIS
ex. oxygen diffusing from lungs into the bloodstream
- Water and dissolved solutes dissolve freely in extracellular fluids
- Ions or molecules can only diffuse across a selectively permeable plasma membrane (selective diffusion) by crossing the lipid portion or passing through a membrane channel
3.15 Explain the process of osmosis, and identify its significance in the body. p. 122
Osmosis is the diffusion of water molecules across a selectively permeable membrane. HELPS MAINTAIN HOMEOSTASIS
Intracellular and extracellular equilibrium persists because a typical plasma membrane is freely permeable to water.
A HYPOtonic solution causes water to flow into the cell. May cause hemolysis, or the red blood cell to burst.
A HYPERtonic solution results in the osmotic movement of water out of the cells. The shrinking of red blood cells is called crenation.
An ISOtonic solution does not cause an osmotic flow of water into or out of the cell.
