Cell Theory and Eukaryotic Cell Structure

The main takeaway is that the cell theory states the cell is the basic unit of life, all living things are made of cells, and cells come from other cells.

### Biology Study Guide: Cell Theory, Cell Structure, and Chemistry Basics
* 🔬 The cell theory states that the cell is the **basic unit of life**, all living things are made of cells, and cells come from other cells. There are two basic types of cells: **eukaryotic cells**, which have a nucleus, and **prokaryotic cells**, which do not have a nucleus.
* All cells have four components: genetic material (DNA), a plasma membrane, ribosomes, and cytoplasm. The plasma membrane is made of a **phospholipid bilayer**, with **hydrophilic heads facing outward and inward**, and **hydrophobic tails facing each other**.
* 🏗 The fluid mosaic model describes the plasma membrane as a **fluid structure** composed mostly of phospholipids, with **embedded proteins, sugars, and cholesterol**.
* ⚛ The nucleus is an organelle that houses the genetic material (DNA) and has a double membrane with pores. **Chromatin and chromosomes** refer to different forms of packaged DNA.
* 🔌 The endoplasmic reticulum (ER) has two types: **rough ER (with ribosomes for protein synthesis)** and **smooth ER (for lipid synthesis)**. The Golgi apparatus **modifies and packages proteins and lipids**.
* 🗑 Lysosomes are vesicles that contain digestive enzymes to **break down old or worn-out cell components**. Mitochondria and chloroplasts are energy organelles with **double membranes and their own DNA**.
* The cytoskeleton provides support and helps in organelle movement. The cell wall, made of cellulose in plant cells, **provides structure and support**.
* 🔬 The extracellular matrix is produced by animal cells and consists of **proteins and other molecules**. Cell junctions, like gap junctions, tight junctions, and desmosomes, help **hold cells together**.
* 🔬 The scientific method involves making observations, proposing hypotheses, conducting experiments, collecting data, and **drawing conclusions**. Independent variables are **manipulated**, while dependent variables are **measured**.
* 🌱 All living things share characteristics such as **order, response to stimuli, reproduction, growth and development, regulation, energy processing, and homeostasis**.
* The four most common elements in living things are **carbon, hydrogen, oxygen, and nitrogen**. An element is a substance that **cannot be broken down into simpler substances by chemical means**.

### Structure and Properties of Atoms, Bonding, and Biological Molecules
* ⚛ Atoms consist of **protons, neutrons, and electrons**. The atomic number indicates the number of **protons**, while the atomic mass includes **protons and neutrons**. For an electrically neutral atom, the number of **protons equals the number of electrons**.
* 🔗 Atoms form bonds by either **giving, taking, or sharing electrons** to fill their valence shell. Ionic bonds are formed when atoms **gain or lose electrons**, creating charged particles. Covalent bonds are the strongest bonds, formed by **sharing electrons**.
* 💧 Hydrogen bonds are weak bonds formed between already bonded molecules. In water, hydrogen bonds lead to various unique properties, such as **high surface tension** and **ice being less dense than liquid water**.
* - Solutions consist of a solvent (e.g., water) and a solute.
- Acids increase the concentration of hydrogen ions, **lowering the pH**, while bases reduce the concentration, **raising the pH**.
- Buffers help **maintain a stable pH** in the body.
* 🌿 The four biological macromolecules are carbohydrates, nucleic acids, proteins, and lipids. They are polymers made up of **monomers**. Carbohydrates' monomer is a **monosaccharide**, while nucleic acids' monomer is a **nucleotide**.
* 🥩 Proteins' monomer is an amino acid, with **20 different types**. Proteins have a primary structure (sequence of amino acids), secondary structure (local folding), tertiary structure (overall 3D shape), and quaternary structure (interaction of multiple polypeptides).
* 🧂 Lipids include fats (triglycerides), phospholipids, steroids, and waxes. Fats are formed by **glycerol and fatty acids**. Saturated fats have all carbons **saturated with hydrogens**, while unsaturated fats have **double bonds**.
* 🚫 Trans fats are unsaturated fats with a trans double bond configuration, often created through hydrogenation. They have adverse health effects due to their **unnatural structure**.

Biology 1408 Lecture Exam 1 - Review

Natalie Russell

Understanding the Cell Theory and Cell Structure

The cell theory states that the cell is the basic unit of life, all living things are made of cells, and cells come from other cells.

Eukaryotic cells have a nucleus and other organelles, while prokaryotic cells have a simple structure without a nucleus.

All cells have genetic material, a plasma membrane, ribosomes, and cytoplasm.

The plasma membrane regulates the passage of molecules and ions, and it is made of a phospholipid bilayer with hydrophilic heads and hydrophobic tails.

The Role of the Plasma Membrane and Organelles in Cell Structure

The plasma membrane is made up of a phospholipid bilayer with polar heads pointing in and out, while the hydrophobic tails are sandwiched in between, providing a barrier between the interior and exterior of the cell.

The fluid mosaic model explains the fluidity and the non-uniform distribution of proteins, sugars, and cholesterol within the membrane.

The nucleus is a membrane-bound organelle that houses genetic material, while the endoplasmic reticulum, consisting of rough and smooth types, is involved in protein and lipid synthesis respectively, playing crucial roles in the structure and function of the cell.

The Role of Golgi Apparatus and Other Cell Organelles

The Golgi apparatus receives vesicles from the rough and smooth ER, modifies the proteins and lipids, and then ships them to their destinations in the cell.

Lysosomes, produced by the Golgi, act as a recycling center, containing digestive enzymes to break down old molecules.

The chloroplast and mitochondria are energy organelles with double membranes, each having its own DNA, and they are responsible for ATP production and photosynthesis, respectively.

The Key Components of a Cell and Their Functions

The cell contains various organelles such as the nucleus, mitochondria, and chloroplasts, each with specific functions.

The central vacuole is unique to plant cells and helps maintain turgidity.

The cell also has junctions like gap junctions, tight junctions, and desmosomes, which play crucial roles in cell communication, forming watertight seals, and holding tissues together.

The Basics of Biology: Cell Junctions, Scientific Method, and Characteristics of Living Things

Cell junctions include tight junctions, gap junctions, and desmosomes, which help cells communicate and stay connected.

The scientific method involves making observations, proposing hypotheses, conducting experiments, collecting data, and drawing conclusions.

Living things share characteristics such as order, response to stimuli, and reproduction, which are essential for their survival and function.

Organisms grow and develop according to their genes' instructions, while regulation and homeostasis maintain internal stability.

All living cells require energy for survival, obtained through various means such as food ingestion or photosynthesis.

The levels of biological organization range from atoms to the biosphere, including populations, communities, and ecosystems.

Biology encompasses three domains: Archaea, Bacteria, and Eukarya, each with distinct cell structures.

The field of biology includes molecular biology, microbiology, neurobiology, paleontology, zoology, botany, and forensic science, all focusing on different aspects of living organisms and matter.

Understanding Atoms: The Basics of Subatomic Particles and the Periodic Table

Atoms are made up of protons, neutrons, and electrons, with the atomic number representing the number of protons and the atomic mass indicating the total number of protons and neutrons.

The nucleus of the atom contains protons and neutrons, while electrons are found in energy shells and are involved in bonding.

When an atom gains or loses electrons, it becomes an ion, resulting in a positive or negative charge.

The Difference Between Ionic and Covalent Bonds

Ionic bonds are formed by the transfer of electrons, creating positively and negatively charged ions, which are then attracted to each other.

Covalent bonds, on the other hand, are formed by the sharing of electrons, which can be either polar or nonpolar depending on the electronegativity of the atoms involved.

Electronegativity determines how tightly an atom holds onto its electrons, resulting in unevenly shared electrons and partial charges in polar covalent bonds.

The Role of Hydrogen Bonds in Water's Unique Properties

Hydrogen bonds in water cause ice to be less dense than liquid water, affecting its ability to float.

These bonds also contribute to water's high surface tension and cohesion, allowing it to be drawn up through plants.

Additionally, water's hydrogen bonding is responsible for its role as a solvent, its high heat capacity, and its resistance to changes in temperature.

Hydrogen ion concentration increases as the strength of the acid increases, while the hydroxide ion concentration increases with a stronger base.

Our body uses buffers to maintain a stable blood pH, avoiding large fluctuations.

The four macromolecules in cells are carbohydrates, nucleic acids, proteins, and lipids, each consisting of monomers and polymers, with specific functions in the body.

The Role of Polysaccharides, Proteins, and Nucleic Acids in Biology

Polysaccharides like cellulose, chitin, glycogen, and starch are important for structural support and energy storage in living organisms.

Proteins are built from 20 different amino acids and their structure is determined by DNA, with a crucial three-dimensional shape that impacts their function.

Nucleic acids, the monomer being a nucleotide, are essential for storing and expressing genetic information, with DNA and RNA using a similar alphabet of bases for this purpose.

The Structure of Nucleotides, Steroids, and Fats

Nucleotides consist of a phosphate, a sugar, and a base, which can be adenine, guanine, cytosine, thymine (in DNA), or uracil (in RNA).

Steroids, such as testosterone and estrogen, share a common ring structure but have different parts coming off the rings.

Triglycerides, known as fats, are composed of glycerol and three fatty acids, and the type of fatty acid and its bonds determine if it's saturated, monounsaturated, or polyunsaturated, impacting its consistency at room temperature.

Trans fats, mostly man-made, have a different shape than natural fatty acids, leading to a buildup in the body and causing health issues.