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

Understanding Cells: The Building Blocks of Life

Cells are the fundamental building blocks of all living organisms.

Cell Structure Essentials

A typical cell consists of several key components:

• Plasma membrane: A very thin, stretchy cover composed of lipids, proteins, and carbohydrates that separates the cell from its external environment.
• Cytoplasm: The jelly-like substance filling the cell, enclosing the organelles.
• Genetic material (DNA): A complex chemical substance containing the genetic information necessary to regulate the cell's functions.

Prokaryotic vs. Eukaryotic Cells

Cells are broadly classified into two types based on the location and organization of their DNA:

Prokaryotic Cell Characteristics

• Kingdom: Monera (bacteria).
• Cellularity: Typically

Cellular Respiration Stages

Glycolysis: Sugar Breakdown

Breaks down a 6-carbon sugar into two 3-carbon groups.

Krebs Cycle Location and Output

Occurs in the inner membrane of the mitochondria.

Forms 2 ATP.

ETC and ATP Synthase Function

Finishes the breakdown of pyruvic acid molecules to CO₂.

Forms 34 ATP.

ATP and ADP Explained

ATP (Adenosine Triphosphate) becomes ADP (Adenosine Diphosphate) when one phosphate is given away, leaving only two.

ADP becomes ATP when one phosphate is added to complete the three phosphates.

Electron Transport Chain Role

A sequence of electron carrier molecules that transfers electrons and releases energy during cellular respiration.

Fermentation: ATP Without Oxygen

When cells exercise and there is not enough O₂, they use fermentation... Continue reading "Biology Essentials: Cells, Respiration, Anatomy" »

Photosynthesis produces glucose using

Photosynthesis produces food in plants, called glucose. It happens in chloroplasts. Chloroplasts contain chlorophyll, that absorbs sunlight and uses its energy to convert carbon dioxide and water into glucose. Oxygen is also produced. EQUATION: CARBON DIOXIODE + WATER= GLUCOSE + OKYGEN. Photosynthesis converts light energy into chemical energy.

Adaptation for efficient photosynthesis

Leaves are broad so there is a large surface area exposed to light. Most of chloroplasts are found in the palaside layer. This is so that they are near the top of the leaf where they can get the most light. The upper epidermis is transparent so that light can pass through it to the palisade layer. Leaves have a network of vascular... Continue reading "Photosynthesis and Efficient Adaptations for Multicellular Organisms" »

Introduction

In this process, energy, in the form of adenosine triphosphate (ATP), is released and utilized by the cell for basic biological functions. This guide will delve into the intricacies of cellular respiration, exploring its different stages and the molecules involved.

Steps in Cellular Respiration

Oxidation-Reduction (Redox) Reactions

Electrons are transferred from one molecule to another, playing a pivotal role in cellular respiration.

ATP Synthesis Methods

• Substrate-Level Phosphorylation: Depends on the interaction between enzymes.
• Oxidative Phosphorylation: Powered by the proton motive force and occurs through the use of ATP Synthase.

Glycolysis

Glycolysis produces 4 ATP molecules, all formed through the use of a substrate-enzyme complex.... Continue reading "Cellular Respiration: A Comprehensive Guide to Energy Production" »

Proteins are composed of 20 amino acids.

Functional groups influence reactivity.

Nonpolar side chains are green.

Polar side chains are pink.

Electrically charged side chains:

• Acidic: red
• Basic: blue

Condensation reactions form a peptide bond by bonding the carboxyl group of one amino acid to the amino group of another. Multiple peptide bonds create a polypeptide. Polypeptides containing more than 50 amino acids are called proteins.

Protein Structure

Primary structure: The unique sequence of amino acids.

Secondary structure: Hydrogen bonds between the carbonyl group of one amino acid and the amino group of another form a protein's secondary structure.

Secondary structure depends on the primary structure.

Tertiary structure: Results from interactions between... Continue reading "Understanding Protein Structure, Enzymes, and Nucleic Acids" »

Actin Cytoskeleton Dynamics and Regulation

The actin cytoskeleton provides thin, flexible mechanical support to cells. Actin monomers are added and removed at distinct ends of the filaments, influencing their dynamics and cellular functions.

• Actin-ATP Addition: ATP-bound actin is primarily added to the barbed (plus) end of the filament.
• Molecular Timer: Older filaments contain ADP-bound actin, making them unstable and prone to disassembly. This acts as a molecular timer for filament turnover.
• Cellular Movement: Actin dynamics are crucial for various cellular processes, including movement and phagocytosis.

Key Regulators of Actin Filaments

Several proteins precisely control actin filament assembly and disassembly:

• Nucleation Factors: Dictate the rate

Darwin and the Theory of Natural Selection

The principal merit of Darwin's theory, in addition to the many evidence that he provided to it, is the discovery of the mechanism that governs the entire evolutionary process of species: the natural selection.

1. Firstly, when environmental resources become scarce, an inevitable competition occurs and, consequently, the struggle for survival begins in which most individuals die.
2. Secondly, it is also obvious that individuals of the same species have different features or characteristics that appear randomly and make individuals different from each other.
3. Third, these characteristics make some individuals more advantaged than others. Those whose characteristics are favorable to the demands of the environment

Kidney and Urinary Tract Conditions

Renal Failure Explained

Renal failure signifies insufficient filtration of blood at the Malpighian glomeruli. This leads to reduced urine production and inadequate elimination of excretory substances.

Symptoms include nausea, vomiting, seizures, and fainting. If untreated, it can lead to death.

Common causes include:

• Renal injuries
• Deficient blood pressure in the kidneys
• Urine retention due to an obstruction in the urinary tract

Nephritis: Kidney Inflammation

Nephritis is kidney inflammation resulting from infectious or non-infectious causes. Symptoms typically include pain, goosebumps, and fever.

Cystitis: Bladder Inflammation

Cystitis refers to inflammation of the bladder, generally caused by an infection. It results... Continue reading "Human Body Systems: Renal, Reproductive, and Cellular Functions" »

Cellular Energy Production

Cells use energy for all their reactions and processes. These vital processes include:

• Movement
• Making new substances from small molecules
• Growth and repair
• Active transport
• Nerve impulses
• Heat production

Aerobic Respiration: Energy with Oxygen

Aerobic respiration is the release of energy using oxygen. Oxygen is carried by the blood in red blood cells within hemoglobin and diffuses into cells. Glucose also travels to the cells in the blood.

In the cytoplasm of cells, there are specific organelles called mitochondria. Oxygen diffuses into the mitochondria and is used to react with glucose to produce carbon dioxide and water. The chemical energy is transferred to a substance called ATP, which stores a small amount of energy.

The... Continue reading "Cellular Respiration and Human Breathing Explained" »

All Cells Form from Existing Cells

• Centipedes: 1 pair of legs per each section
• Millipedes: 2 pairs per each section

• All organisms are composed of one or more cells
• The cell is the basic unit of life in all living things
• Cells are produced by the division of pre-existing