DNA Replication and Protein Synthesis
Stages of DNA Replication
Introduction
The primosome primases open strands and start helicases, unwinding the double helix. The rest of the replisome gets together with the polymerase, forming replication forks. After opening, the DNA strands bind to SSB proteins that prevent the DNA from renaturing or forming secondary structures. Other enzymes called topoisomerases prevent kinks and the formation of super-enrollments. The DNA polymerase catalyzes the first phosphodiester bond.
Elongation
In this
Environmental Systems and Societies: Key Concepts
Definitions: Test 1
- Open system: A system that exchanges energy and matter with its surroundings.
- Closed system: A system that exchanges only energy with its surroundings.
- Isolated system: A system that doesn’t exchange anything with its surroundings.
- Transfer: Movement of energy or matter from one place to another.
- Transformation: When energy changes from one form to another.
- 1st Law of Thermodynamics: Energy cannot be created or destroyed, only transformed.
- 2nd Law of Thermodynamics: Entropy increases
Understanding the Cardiovascular and Lymphatic Systems
The cardiovascular system consists of:
- A pump (the heart) that circulates fluid (blood).
- A circulating fluid (blood) containing substances and cells that need to be transported.
- A network of vessels through which blood circulates.
It has several functions:
- Transports nutrients from the digestive system to all body tissues.
- Takes oxygen from the respiratory system to cells.
- Collects waste products produced by cell metabolism.
- Takes specialized defense cells and molecules to tissues infected by pathogenic
Plant Responses, Hormones, and Development Stages
Item 2: Plant Responses, Hormones, and Development
The Relation (Stimulus-Response)
Relation is the capacity to formulate a response to a stimulus, i.e., a change that can be both internal and external to the plant. This change is detected by receptors located in the epidermis of the plant. The responses are regulated by phytohormones. Receptors are classified according to the stimuli they detect:
- Photoreceptors: Detect changes in light intensity.
- Chemoreceptors: Detect chemical changes.
- Thermoreceptors:
Cellular Respiration: Krebs Cycle, Electron Transport Chain
Krebs Cycle
The Krebs cycle is the oxidation of the acetyl group of acetyl-CoA to CO2, while reducing NAD and FAD. These reduced coenzymes are subsequently reoxidized by the respiratory chain, generating ATP. It consists of a series of eight enzymatically catalyzed reactions that occur in the mitochondrial matrix:
- Acetyl-CoA condenses with oxaloacetate to yield citrate, a tricarboxylic acid.
- Citrate is converted to isocitrate.
- Oxidative decarboxylation of isocitrate yields alpha-ketoglutarate, forming
Cell Biology: Discoveries, Theory, and Cell Types
Key Discoveries in Cell Biology
Robert Brown’s Contribution
What was the contribution of Robert Brown?
He discovered the cell nucleus through his studies of plant cells by staining the cells.
Johannes Purkinje’s Contribution
What was the contribution of Johannes Purkinje?
He identified the viscous substance (protoplasm) within cells where cell components could move.
The Cell Theory
Scientists Who Established the Cell Theory
- Scheiden Mathias (botanist): All plants are composed of plant cells.
- Schwann Theodor