Biology Chapter: Cell Structure

Key Features of All Cells

• Cells are the basic structural unit of all living organisms.
• Unicellular organisms have only one cell.
• Multicellular organisms have many cells.
• All cells contain genetic material for producing mRNA.
• All cells contain proteins.
• Cytoplasm is composed mainly of water and enzymes for chemical reactions.
• Plasma membrane controls substance movement in and out of the cell. It is made of lipids.

Prokaryotic Cell Structure

• Prokaryotic cells do not have a nucleus.
• They have a nucleoid instead.
• Prokaryotic cells are unicellular.
• They have a single, naked, circular chromosome.
• They have 70s ribosomes for protein production.
• The cytoplasm is the water-like base of the cell.
• The plasma membrane separates the interior from the cell wall.
• The cell wall is the outer layer of the cell.
• Flagella helps the bacteria move.

Eukaryotic Cell Structure

• Eukaryotic cells have a nucleus.
• They have a cell wall.
• Chromosomes comprise DNA and histones (a protein).
• Vesicles transport proteins from the rough endoplasmic reticulum to the Golgi Apparatus/Body.
• The Golgi Apparatus/Body modifies proteins.
• The nucleolus creates 80s ribosomes.
• Ribosomes break down debris using enzymes.
• Mitochondria are the powerhouse of the cells where cellular respiration occurs producing energy (ATP).
• Mitochondria have double membranes for increased surface area.
• Chromatin is the tangled DNA in the nuclear membrane.

Organelles

• Organelles are specialized parts of a cell with special jobs.
• Organelles can be classified by the number of membranes surrounding them.
• Ribosomes have 0 membranes.
• Endoplasmic reticulum, Golgi, lysosomes, and vesicles have 1 membrane.
• Nucleus, mitochondria, and chloroplasts have 2 membranes.

Comparing Eukaryotic Cells

• Animals do not have a cell wall.
• Fungi have cell walls of chitin.
• Plants have cell walls of cellulose.
• Animal cells have small vacuoles, while plants and fungi have large vacuoles.
• Animal cells do not have plastids, while plants have chloroplasts.
• Animal cells have centrioles, while fungi and plants don't.
• Animal cells have cilia/flagella, while some fungi have them, while plants don't generally.

Atypical Eukaryotic Cell Structures

• Red blood cells are anucleate (no nucleus).
• Sieve tube elements are anucleate (no nucleus).
• Multinucleate cells have many nuclei.
• Skeletal muscle fibers are multinucleate.
• Aseptate fungi have thread-like structures called hyphae which contain many nuclei.

Microscopy skills

• Light microscopes use visible light to magnify and view small organisms.
• Electron microscopes provide higher resolutions to view details inside the cell.

Cell Theory

• All living organisms are made from cells.
• Organisms are either unicellular (one cell) or multicellular (many cells).
• Cells come from pre-existing cells.

Life Processes in Organisms

• Both unicellular and multicellular organisms carry out life functions like metabolism, reproduction, movement, excretion, homeostasis, nutrition, growth, and response.

B2.1 Membranes and Membrane Transport

• The fluid mosaic model describes the structure of the cell membrane.
• The membrane is described as a phospholipid bilayer.
• It has integral proteins, peripheral proteins, and carbohydrates attached to it.
• Cholesterol controls fluidity of the cell membrane.
• Passive transport moves with the concentration gradient.
• Simple diffusion is a type of passive transport.
• Facilitated diffusion is when channel proteins change shape.
• Osmosis is another type of passive transport focusing on the movement of water molecules across a membrane.
• Active transport needs energy to move against the concentration gradient.
• Endocytosis is when a cell absorbs large molecules.
• Exocytosis is when a cell expels large molecules.

B2.2 Organelles and Compartmentalization

• Compartmentalization allows cells to specialize functions and create a microenvironment.
• Cell walls are outside the plasma membrane.
• Cytoplasm is not enclosed by a membrane.
• Cytoskeleton is not considered an organelle (it is an extensive structure).
• Lysosomes contain enzymes.
• Nucleus and cytoplasm are separated. (DNA, Transcription, mRNA, Translation, and Protein formation in the nucleus).

A2.3 Cell Size (Specialization)

• Cells come in many different sizes and shapes.
• Volume refers to the amount of space inside a cell
• Surface Area is the area of the cell exposed to the external environment
• Volume increases more rapidly than surface area as cell size increases
• Surface area to volume ratio becomes smaller
• The surface area can be increased by dividing the cell to smaller pieces.

Scientific Method

• Observation, research, hypothesis, experiment, data analysis, and conclusion.

The Human Body Systems

The four types of tissues are:

• Connective tissue
• Epithelial tissue
• Muscle tissue
• Nervous tissue

Cardiovascular Diseases

• Atherosclerosis is the build-up of plaque inside arteries.
• Coronary heart disease is the build-up of plaque inside the coronary artery.
• A blocked blood vessel can cause a heart attack or stroke.

Respiratory System

• The respiratory system's functions are gas exchange and ventilation.
• Respiration is the process of exchanging gases between the body and the outside air.
• Breathing is the two-step process of inhaling and exhaling.
• Aerobic respiration requires oxygen, while anaerobic respiration does not.

Blood Vessels Components

• Arteries carry oxygenated blood away from the heart.
• Veins carry deoxygenated blood toward the heart.
• Capillaries connect arteries and veins.

Blood

• Blood is a fluid connective tissue that carries oxygen, hormones, and nutrients.
• Erythrocytes (red blood cells) contain hemoglobin for oxygen transport.
• Leukocytes (white blood cells) fight against infection.
• Platelets are involved in blood clotting.

Respiratory Diseases

• Asthma
• Pneumonia
• Emphysema
• COPD
• Lung Cancer