Chapter 5II
Define chromatin.
DNA molecules in a cell packaged with proteins.
Compare and contrast prokaryotic cells with eukaryotic cells.
Prokaryotes:
Unicellular
evolutionary older
no nucleus
no membrane bound organelles
DNA is free floating in the cytoplasm
Eukaryotes:
DNA in nucleus (bound by the nuclear envelope)-
Membrane-bound organelles
Cytoplasm between the plasma membrane and the nucleus
Younger: first fossils ~1.5bya
Multicellular & Unicellular
Both
-Plasma membrane
-Ribosomes
-Cytoplasm
-DNA
What does amphipathic mean?
They have hydrophobic & hydrophilic regions
Explain anabolic and catabolic pathways. Give an example of each.
Catabolic pathways- release energy by breaking down complex molecules into simpler compounds EX: cellular respiration, the breakdown of glucose in the presence of oxygen
Anabolic pathways- consume energy to build complex molecules from simpler ones
EX: synthesis of protein from amino acids
Mitochondria
Place of cellular respiration: Break down organic molecules & convert energy to a form cells can use for work (ATP) Powerhouse of the cell
Draw an amino acids on the board and label its parts.
Amine group, carboxyl group and side chain (R group), alpha carbon
What is a ribosome? What is its function? Where are ribosomes found within the cell?
Ribosomes are complexes made of ribosomal RNA and protein. They are found bound to the rough ER and free in the cytoplasm. They translate sequence of nucleotides in mRNA into amino acid sequence of polypeptides.
What is the difference between channel proteins and carrier proteins?
-Channel proteins have a hydrophilic channel that certain molecules use a tunnel (aquaporins)
-Carrier proteins hold on to passengers and change shape in a way that shuttles them across
What are the three types of work conducted in a cell? Give examples.
Chemical: The pushing of endergonic reactions that would not occur spontaneously (synthesis of polymers from monomers)
Mechanical: Moving a muscle cell
Transport: The pumping of substances across membranes against the direction of spontaneous movement.
Plasma Membrane
-Selectively Permeable
-Very thin layer of lipids (two fat molecules thick - phospholipid bilayer)
-controls what leaves and enters the cell
Name the four nucleotides present in DNA and RNA.
DNA: Adenine, Guanine, Cytosine, Thymine
RNA: Adenine, Guanine, Cytosine, Uracil
What does the endomembrane system consist of? (Hint: 6)
-Nuclear envelope
-Endoplasmic Reticulum
-Golgi Apparatus
-Lysosomes
-Vacuoles
-Plasma membrane
Explain hypotonic, isotonic, and hypertonic. What is osmosis?
Hypotonic –has lower solute concentration
Isotonic –same concentrations inside/outside
Hypertonic –has higher solute concentration
Osmosis - water moves until solution concentrations on both sides are equal, passive transport of water, water moves down its own concentration gradient
What is the difference between an exergonic reaction and a endergonic reaction?
Exergonic reaction:
proceeds with a net release of free energy (ΔG<0) and is spontaneous (EX: catabolism of glucose)
Endergonic reaction:
absorbs free energy from its surroundings (ΔG>0) and is non-spontaneous (e.g. anabolism of glucose)
Photosynthesis is strongly endergonic
Golgi Apparatus
modify, store and route products of the endoplasmic reticulum and synthesize some products.
Explain and describe the four levels of protein structure.
Primary, Secondary, Tertiary, and Quaternary Structure.
Compare and contrast the mitochondria and chloroplasts.
Both:
- Have a double membrane with their inner membrane space
-Have their own DNA: reproduce themselves and make some of their own proteins
Mitochondria:
-Cristae: folds of the inner membrane
-Matrix: fluid-filled space
-In animal and plant cells
Chloroplasts:
-Converts solar energy to chemical energy
-Only in plant cells
-Contains chlorophyll- absorbs solar energy
-Stroma: fluid within chloroplasts
-Thylakoids: flattened connected stacks of membranes
Looking at the image, describe how osmosis occurs through this selectively permeable membrane in the U-shaped tube.
Water moves until solution concentrations on both sides are equal = osmosis
Describe enzymes and their functions.
Proteins that act as catalysts
-speed up reactions without being consumed by the reaction and are substrate specific
Endoplasmic Reticulum
Smooth ER- Lipid synthesis, detox cell, no bound ribosomes
Rough ER- bound ribosomes, makes proteins
List the functions of proteins and an example for each.
Enzymatic, Defensive, Storage, Transport, Hormonal, Receptor, Contractile & Motor, Structural
Name specific functions of the cytoskeleton. Explain what microtubules and microfilaments are.
Cell shape- microtubules and microfilaments
Internal Organization- microtubules
Cell motility- microtubules and microfilaments
Intracellular Transport- microtubules
Explain endocytosis. What are the three types of endocytosis?
Cell takes in molecules by forming new membrane vesicles from the plasma membrane
Phagocytosis- cell is “eating” (later broken down by enzymes)
Pinocytosis – cell is “drinking” (already broken down or dissolved food)
Receptor mediated endocytosis- ligands bind to specific protein receptors on the cell’s surface which allow them to be engulfed by the cell
Is the human body a closed or open system? Why or why not?
It is an open system because closed systems will reach equilibrium and no more work can be done. Cells are not in equilibrium and experience a constant flow of materials.
Lysosomes
-Originate in the Golgi
-Membranous sacs of enzymes used by animals to hydrolyze macromolecules - Phagocytosis
-Also break down damaged organelles so parts can be recycled - Autophagy (cell recycling)