4.2 Flashcards
Compare and contrast animal and plant cells.
Animal cells
- flagellum
Plant cells
- Central vacuole (stores proteins, pigments and waste material)
- Chloroplast
- Cell wall
Describe characteristic features of the nucleus.
-control center of the cell
o Repository of the genetic information
o DNA is organized into units called chromosomes
o Nucleolus
Located within the nucleus and the site of rRNA synthesis
o Nuclear envelope
Encloses the nucleus
Separates it from the cytoplasm
Double membrane
• 2 phospholipid bilayers
Nuclear pores regulate the entry and exit of molecules from the nucleus
o Nuclear lamina
Composed of proteins and maintains the shape of the nucleus
Describe the role of ribosomes in protein synthesis.
Ribosomes travel along strands of mRNA and provide tRNA to attach based on the codon sequence. Amino acids then form peptide bonds with the end of the polypeptide strand. In the Ribosome mRNA, tRNA and amino acids come together to form a protein
Identify the parts of the endomembrane system
-ER
-Golgi Apparatus
-Lysosomes
-Vacuole
-plasma membrane
describe the role of the ER in the cell.
• Accounts for more than half of the total membrane in many eukaryotic cells
• (Continuous with) nuclear envelope
• Rough ER
-ribosomes on outside
-processes proteins produced by ribosomes
• smooth ER
-synthesizes lipids, phospholipids and steroids
describe the role of the golgi apparatus in the cell.
• processes and packages proteins and lipids produced by the cell
• Consists of flattened membranous sacs called cisternae
• Cis face
o Receiving side located near the ER
• Trans face
o Transport vesicles discharge
describe the role of the lysosomes in the cell.
• contain digestive enzymes to engulf aged organelles, food, and bacteria
o phagocytosis
lysosome fuses with the food vacuole and digests the molecules
autophagy
• use enzymes to recycle the cell’s own organelles and macromolecules
describe the role of the plasma membrane in the cell
-double layer of phospholipid
-encloses everything inside the cells and allows for passage of molecules in and out of the cell
describe the role of the vacuoles in the cell.
• Large vesicles derived from the ER and golgi apparatus
o Functions
Food vacuoles
• Formed by phagocytosis
Contractile vacuoles
• Found in many freshwater protists, pump excess water out of cells
Central vacuoles
• Found in many mature plant cells, hold organic compounds and water
Differentiate the structure and function of the rough and smooth endoplasmic reticulum.
Rough ER
- Has bound ribosomes
- Secrete glycoproteins which covalently bond to carbohydrates
- Distribute transport vesicles (secretory proteins surrounded by membranes)
- Membrane factory for the cell
Smooth ER
- Synthesizes lipids which are steroid hormones
- Synthesizes carbohydrates
- Stores intracellular calcium ions (Ca2+) which are involved in muscle contraction
- Detoxification (drugs and poisons)
Same
- Biosynthetic factory
- Account for more than half of the total membrane in many eukaryotic cells
- Continuous with the nuclear envelope
Identify the functions of the Golgi apparatus.
o Modifies products of the ER
Glycoproteins and glycolipids
o Manufactures certain macromolecules
Cell wall components
o Sorts and packages materials intro transport vesicles
Contrast the functions of lysosomes, microbodies (peroxisomes), and vacuoles.
lysosomes
- a membranous sac of hydrolytic enzymes that can digest macromolecules
- Arise from the golgi apparatus
- Contain high levels of enzymes that degrade proteins, nucleic acids, lipids, carbohydrates, and even cells
- Some can engulf another cell by phagocytosis which forms a food vacuole when a lysosome fuses with the food vacuole and digests the molecules
- Autophagy: use enzymes to recycle the cell’s own organelles and macromolecules
Microbodies (peroxisomes)
- Involved in the oxidation of fatty acids
- Produce hydrogen peroxide as a by-product
vacuoles
- Food vacuoles are formed by phagocytosis
- Contractile vacuoles are found in many freshwater protists, pump excess water out of cells
- Central vacuoles are found in many mature plant cells and hold organic compounds and water
Compare and contrast the structures and functions of the mitochondria and chloroplasts.
mitochondria
- Site of cellular respiration (A metabolic process that uses oxygen to generate ATP) for all eukaryotic cells
chloroplasts
- Site of photosynthesis
- Found in plants and algae
SAME
- Change energy from one form to another
- Endosymbiont theory (Have similarities with bacteria (enveloped by a double membrane, contain free ribosomes and circular DNA molecules, grow and reproduce somewhat independently in cells))
Explain the probable origin of the mitochondria and chloroplast.
A prokaryote was engulfed by and became part of another cell, which was the precursor of modern eukaryotes
Contrast the structures of the three types of cytoskeletal fibers and list their functions.
Microtubules
- Largest of the cytoskeletal elements
- Dimers of alpha and ß tubulin subunits
- Facilitate movement of cell and materials within cell
Microfilaments/Actin
- two protein chains loosely twined together
- movements like contraction, crawling, “pinching”
- motor proteins
Intermediate filaments
- between the size of actin filaments and microtubules
- very stable-usually not broken down
- support cell shape, anchors organelles, forms nuclear lamina
