Notes, summaries, assignments, exams, and problems for Biology

Structural Components of Viruses

• Capsid: Protein shell that encloses a viral genome; may be rod-shaped, polyhedral, or more complex in shape
• Viral envelopes: Membrane that cloaks the capsid that in turn encloses a viral genome

Obligate Intracellular Parasites

Viruses can only reproduce within host cells because they lack metabolic enzymes, ribosomes, and other equipment for making proteins.

• Identifying host cells: "Lock and key" fit between proteins on the outside of the virus and specific receptor molecules on the host's surface (which originally evolved for functions that benefit the host).

Bacterial Defenses Against Phages

While phages have the potential to wipe out a bacterial colony in just hours, bacteria have defenses against phages:

• Natural

Evolutionary Theories

Punctuated Equilibrium vs. Neo-Darwinism vs. Neutralism

• All three theories propose evolutionary change.
• Punctuated Equilibrium: Evolutionary changes occur rapidly and abruptly.
• Neo-Darwinism: Evolutionary changes occur gradually over time.
• Neutralism: Most mutations have no effect on natural selection.

Barriers to Genetic Isolation

• Geographical
• Sexual
• Physiological
• Chromosomal
• Ethological

Ecological Concepts

Abiotic and Biotic Factors

• Abiotic Factors: Non-living factors that affect ecosystems (e.g., temperature, pH, wind)
• Biotic Factors: Living components that affect ecosystems (e.g., disease, predation, competition)

Biomass

- Total dry weight of organic matter in organisms or ecosystems. - Includes carbohydrates, proteins, etc.

Ecosystems

Proteins

  

∑ - Amino acids are linked together by condensation to form polypeptides.

• Amino acids are then combined to create large polypeptides through condensation reactions which produce many molecules of water (i.e. polypeptides - Hemoglobin and Insulin).

B  Skill: Drawing molecular diagrams to show the formation of a peptide bond.

• Basic dipeptide shown to the right. Students should practice drawing  with a variety of different amino acids (different “R” groups)
  
• Every peptide bond should be between the NH2 (amine group) and the COOH (carboxyl group). One H comes from the NH2 and an –OH group comes from the –COOH group to produce H2O
  
• Condensation reaction
  

∑ - There are 20 different amino acids in polypeptides synthesized on ribosomes.

Complete the statements.

1. There are 206 bones in the skeletal system of an adult.
2. Babies are born with almost 300 bones in their body.
3. The largest bone in the body is the femur.
4. The only floating bone is called the hyoid and it is located under the tongue.
5. The skeletal system has two main jobs: protect and support.

Complete the table with the functions of the skeletal system.

Label the parts of the skeletal system.

• Bones: They

Applications of Proteins

Rubisco

• Catalyzes the CO₂ fixation reaction in the Calvin cycle.
• Full name: ribulose bisphosphate carboxylase.
• One of the most abundant and important enzymes.

Insulin

• Hormone produced by pancreatic beta cells.
• Reduces blood glucose levels by promoting glucose absorption.
• Binds reversibly to cell membrane receptors.

Immunoglobulins (Antibodies)

• Y-shaped proteins produced by plasma B cells.
• Identify and neutralize foreign pathogens.
• Act as markers for pathogen destruction by phagocytes.
• Each antibody is specific to a particular pathogen.

Rhodopsin

• Biological pigment in retinal photoreceptor cells.
• Consists of a retinal molecule surrounded by an opsin polypeptide.
• Light absorption changes its shape, sending a nerve impulse to the brain.

Balanced Diet and Nutrients

We need to eat a wide variety of foods to obtain all the necessary substances. A diet that includes a variety of foods is called a balanced diet. Carbohydrates, proteins, fats and oils (lipids), vitamins, and minerals are essential nutrients. These nutrients provide the raw materials our bodies need to function properly.

Food Testing

We can conduct tests to identify the substances present in our food. For example, starch turns iodine a blue-black color.

Nutrition Information Labels

Nutrition information labels on food products tell us about the food's composition and the amount of energy stored within it. Energy is measured in kilojoules (kJ). A person's daily energy needs depend on several factors:

• Level of activity
• Age
• Gender

Food... Continue reading "Balanced Diet and Nutrition: A Guide to Healthy Eating" »

The Nervous System

Central Nervous System (CNS)

Brain

Located inside the head, the brain is divided into three regions:

• Cerebrum: Receives and interprets information from the sense organs. Language, memory, learning, and thinking are located here.
• Cerebellum: Plays an important role in motor control and motor learning. It acts in coordination and precision.
• Brain Stem: Joins the brain and spinal cord. It controls involuntary actions.

Spinal Cord

A long, thin tube running inside the backbone, the spinal cord transports information from the brain to the nerves and carries reflexes.

Protection of the CNS

• Hard: Bones protect the CNS. The brain is protected by the skull, and the spinal cord is protected by the backbone.
• Soft: Meninges, a system of membranes