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

vitamin a : fish liver oils, animal liver. Function: required for normal immune system function and for production of cells in retina of eye. 

Microorganisms: Bacteria and Viruses

Bacteria: Key Characteristics

Bacteria are single-celled, prokaryotic microorganisms. They possess ribosomes, typically around 1000nm in size.

Viruses: Key Characteristics

Viruses are non-cellular genetic elements that are obligate intracellular parasites, meaning they must use living cells to reproduce. Their size ranges from approximately 20-300nm.

Viral Structure Explained

A typical viral structure includes:

• Nucleic Acid (Genome): This is the genetic material, which can be either DNA or RNA.
• Capsomeres: Protein subunits that assemble to form the capsid.
• Viral Nucleocapsid: The combined structure of the nucleic acid and its surrounding protein capsid.
• Core Wall (Capsid/Envelope): A protective shell, often referred

• Ecology is the scientific study of the interactions between organisms and the living and nonliving components of their environment.
• Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges.
• A population is a group of individuals of the same species living in an area.
• Population ecology focuses on factors affecting population size over time.
• A community is a group of populations of different species in an area.
• Community ecology examines the effect of interspecific interactions on community structure and organization.
• An ecosystem is the community of organisms in an area and the physical factors with which they interact.
• Ecosystem ecology emphasizes energy flow and chemical cycling

DNA Deoxyribonucleic Acid Forming Chromosomes

Stores genetic info DNA wounded to histones which becomes nucleosome loops onto chromatin

Codes for protein twisted into chromatid looped and packed into chromosome

Nucleotide Chromatin fibers are coiled and condensed to form chromosomes

consisting of a nitrogen-containing base Histones are proteins that help package and organize DNA in the nucleus of

(a, g, t, c.) or uracil in RNA eukaryotic cells by forming nucleosomes around which DNA is wrapped.

- phosphate group nucleosome is a basic unit of DNA packaging in eukaryotic cells

- sugar chromatid is one of the two identical copies of a replicated chromosome

Homologous Chromosomes chromosome is a long, coiled-up strand of DNA that contains genetic information

chromosomes... Continue reading "Understanding DNA, Chromosomes, and Genetic Variation" »

Sexual Reproduction & Meiosis

Sexual Reproduction: Takes place when two sex cells, or gametes, from two parents of different sexes join together.

Meiosis: A cell division process through which haploid cells are formed.

Fundamental Genetic Concepts

• Traits: Each of the characteristics present in an organism that can be inherited by its offspring.
• Gene: A section of DNA that contains information about a certain trait and controls that trait.
• Alleles: Different forms of a gene.
• Homozygous: When two alleles for a specific trait are identical (e.g., AA, aa).
• Heterozygous: When two alleles for a specific trait are different (e.g., Aa).
• Genotype: An organism's complete set of genes.
• Phenotype: The observable way in which a genotype is expressed under specific

Trophic Levels

A trophic level consists of all organisms within an ecosystem that share the same feeding strategy.

Producers

Producers are autotrophic organisms that perform photosynthesis, using solar energy to convert inorganic matter into organic matter.

Consumers

Consumers are heterotrophic organisms that obtain energy by consuming other living organisms.

Primary Consumers

Primary consumers are herbivores that feed directly on producers.

Secondary Consumers

Secondary consumers are carnivores that feed on primary consumers.

Tertiary Consumers

Tertiary consumers (supercarnivores) are carnivores that feed on secondary consumers, such as lions.

Decomposers

Decomposers are heterotrophic organisms that break down dead organisms and waste products, returning... Continue reading "Ecosystem Dynamics: Trophic Levels, Food Chains, and Energy Flow" »

Cardiovascular System: Key Definitions

Cardiovascular Disease

It can be caused by smoking, poor diet, stress, physical inactivity, or hereditary factors.

Atherosclerosis

It is the hardening of artery walls caused by the buildup of cholesterol and lipids.

Hypertension

It is abnormally high blood pressure.

Heart Attack

It occurs when an artery that supplies blood to the heart becomes blocked.

Stroke

It occurs when a blood vessel in the brain becomes blocked or bursts.

Respiratory System Anatomy

The main parts of the respiratory system include:

• Nasal Cavities
• Mouth
• Pharynx
• Larynx
• Trachea (Windpipe)
• Bronchus
• Bronchiole
• Alveoli
• Lungs
• Diaphragm

Respiratory System Part Identification

1. It is the organ that produces the sense of smell: Nose/Nasal Cavity
2. It is also known as the

Allele Frequencies

Change in allele frequencies can be caused by:

• Natural selection
• Mutation
• Gene flow
• Genetic drift

Viral Reproduction

Steps of viral reproduction:

1. Attachment
2. Entry
3. Integration
4. Synthesis of viral components
5. Viral assembly
6. Release

Antibody Variable Regions

Primary function of the variable regions in antibodies: To bind specifically to antigens and determine the antibody's specificity.

Immunity

Innate Immunity

Innate (aka nonspecific) immunity is present at birth and functions the same way regardless of the pathogen. It involves:

• Phagocytosis
• Inflammation

In response to injury and/or pathogens, innate immune cells release paracrine signaling molecules such as cytokines and histamine that trigger inflammation. External pathogen features that can be... Continue reading "Biology Concepts Review" »

21)Signal Transduction is a process by which an extracellular signal molecule, called the first messenger activates a membrane receptor that in turn alters intracellular molecules, called the secondary messenger, to create a response.