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The cell theory and homeostasis
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WHERE DO CELLS COME FROM?
The cell theory With the invention of the microscope and the help of many different scientists, a very important questions was answered in the 1850’s: WHERE DO CELLS COME FROM?
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The cell theory There are 3 concepts to the cell theory:
Every living thing is made up of one or more cells Cells are the smallest unit of life All cells come from preexisting cells
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Every living thing is made up of one or more cells
There are two types of cells: Prokaryotic First cell to evolve No nucleus DNA (genetic information) contained in the cytoplasm of the cell Growth is usually through the expansion of the cell Examples: Archaea and Bacteria Eukaryotic Evolved from prokaryotes Have a nucleus DNA contained within the membrane-bound nucleus Growth is usually through an increase in number of cells Examples: Animals, Protists, Fungi, Plants
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Every living things is made up of one or more cells
Prokaryotes are unicellular. This means that all functions of life happen within that one cell Eukaryotes are unicellular (protists) and multicellular. If the organism is multicellular, different cells have different jobs and they all work together to perform the functions of life Both unicellular and multicellular organisms follow the 6 characteristics of life
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The functions/characteristics of life
Organization Living things have specialized structures with specialized functions Growth and Development When organisms grow, they increase in size (unicellular) or number of cells (multicellular). Changes that occur in an organism during its lifetime are called development. Reproduction The process by which one organism makes one or more new organisms Not all organisms of a species must reproduce in order for the species to survive (only some need to)
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The functions/characteristics of life
Response to Stimuli When an organism responds to changes in its internal or external environment Internal stimuli are responses to needs within the body (hunger, aches, etc.) External stimuli are responses to needs outside of the body (fear, sunlight, etc.) Homeostasis An organism’s ability to maintain steady internal conditions when outside conditions change Use of Energy Cells continuously use energy to transport substances, make new cells, and perform chemical reactions. People use energy for everyday tasks like sleeping, eating, etc. Things that have all the characteristics of life are called organisms
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The cell organelles
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organelles The size and shape of a cell relates to its job or function
A cell is made of different structures that perform different functions and keep a cell alive. These structures also have unique functions Organelles are tiny membrane-bound structures that perform special functions in the cell
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Cell wall Only found in plant, fungi, bacteria, and some protist cells
Rigid and strong to hold the cell’s shape Provides support and protection for the cell
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Cell/plasma membrane Found in all cell types Provides the cell with
In plant cells, it lies beneath the cell wall In animal cells, it is the outer boundary Provides the cell with Protection Control of the movement of materials in and out of the cell Support Maintains the internal conditions of the cell
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nucleus Found in both plant and animal cells
Consists of the nuclear membrane, nucleoplasm, and nucleolus Controls cell activities and contains DNA The nucleolus makes ribosomes
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Cytoplasm and the Cytoskeleton
Found in both plant and animal cells Cytoplasm is thick, jelly-like substance located beneath the cell membrane that supports and protects the cell’s organelles The cytoskeleton gives the cell its shape and helps it move
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Golgi apparatus Found in both plant and animal cells
Looks like a flattened stack of pancakes Processes and packages molecules made by the cell for transport around the cell or out of the cell in vesicles
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ribosomes Found in both plant and animal cells
Can be found attached the endoplasmic reticulum or floating free in the cytoplasm Produces proteins The smallest organelles
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Endoplasmic reticulum
Found in both plant and animal cells Network of tubes that transports materials throughout the cell Two types: Smooth ER (no ribosomes) Makes lipids and removes harmful substances Rough ER (has ribosomes) Site of protein production
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mitochondria Found in both plant and animal cells
Breaks down sugar molecules to release energy for the cell to use Known as the “powerhouse” of the cell Has inner folds called cristae to increase its surface area
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vacuoles Found in both plant and animal cells
In plant cells, there are very few of them but they are very large In animal cells, they have very many little ones They are fluid-filled sacs that store food, water, and waste
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lysosomes Found only in animal cells
Break down larger food molecules into small food molecules Digest old cell parts
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chloroplasts Found only in plant cells
Green in color because of chlorophyll Use energy from the sun to make food for the plant
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Levels of life’s organization
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It all adds up All matter is composed of atoms and atoms combine to form molecules All living organisms are made of cells (which are composed of molecules)….but how do those cells make organisms? Cells build together to make tissues Tissues build together to make organs Organs build together to make organ systems Organ systems build together to make organisms
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Cells build together to make tissues
The process by which cells become different types of cells is called cell differentiation In multicellular organisms, similar types of cells are organized together into groups. Tissues are groups of similar types of cells that work together to carry out a specific task
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Types of tissues Humans have four types of tissues:
Muscle – causes movement Connective – provides structure and support Nervous – carries messages to and from the brain Epithelial – forms the protective outer layer of skin and lining of major organs Plants have three types of tissues: Dermal – provides protection and prevents water loss Vascular – transports water and nutrients Ground – provides storage and support; where photosynthesis takes place
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Tissues build together to make organs
Complex jobs in the body require the use of more than one type of tissue Organs are groups of tissues working together to perform a particular job Organs usually involve all four types of tissues in humans and all three types of tissues in plants
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Organs build together to make organ systems
Organs do not usually function alone Organ systems are groups of different organs that work together to complete a series of tasks Humans have 11 different organ systems in their body and plants have 2
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Organ systems build together to make organisms
Multicellular organisms usually have many different organ systems that work together to perform daily life tasks that are needed for the survival of that organism
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Human Body Systems
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Interactions with Other Systems
Function Diagram Major Organs Interactions with Other Systems Digestive 1. take in food (ingestion) 2. digest food into smaller molecules and absorb nutrients 3. Remove undigestable food from body (feces) Mouth, esophagus, stomach, Sm. Intestine, Lg. intestine, rectum, anus Salivary glands 1. w/circulatory – absorb & deliver the digested nutrients to the cells 2. w/muscular – control the contractions of many of the digestive organs to pass food along 3.w/nervous –hypothalamus maintains homeostasis by triggering appetite (stomach growling), digest. Respiratory Takes in oxygen and removes carbon dioxide and water Nose Trachea Bronchi Bronchioles Alveoli lungs 1. w/circulatory – takes in O2 for delivery to cells and removes CO2 brought from cells 2. w/excretory – removes excretory waste 3. w/nervous – controls breathing 4. w/muscular – diaphragm controls Breathing
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Interactions with Other Systems
Function Diagram Major Organs Interactions with Other Systems Circulatory Transport materials to and from cells Heart Veins Arteries Capillaries Red blood cells 1. w/respiratory – deliver O2 from lungs to cells and drop off CO2 from cells to lungs 2. w/digestive – absorb and deliver digested nutrients to cells 3. w/excretory – kidneys filter cellular waste out of blood for removal 4. w/lymphatic – both transport things to and from cells 5. w/immune – transports WBCs throughout body to fight disease 6. w/nervous – brain controls heartbeat 7. w/endocrine – trans. Hormones Reproductive Allows organisms to reproduce which prevents their species from becoming extinct. Ovaries *produce eggs Testes *produce sperm 1. w/endocrine – controls production of sex cells 2. w/muscular – uterus contracts to give birth – controlled by hormones
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Interactions with Other Systems
Function Diagram Major Organs Interactions with Other Systems Excretory 1. removes waste products from cellular metabolism (urea, water, CO2) 2. filters blood Kidneys Ureters Bladder Urethra 1. w/circulatory – filters waste out of blood 2. w/lungs –removes excretory waste 3. w/integumentary – removes excretory waste Immune Fights off foreign invaders in the body White Blood Cells *T cells *B cells -produce antibodies *Macrophages Skin 1. w/circulatory – transports WBCs to fight invaders 2. w/lymphatic – has lots of WBCs to fight invaders, spleen filters bacteria/viruses out of blood 3. w/skeletal – WBCs made in bone marrow 4. w/integumentary – prevents invaders from getting in Nervous 1. gathers and interprets information 2. responds to 3. helps maintain homeostasis Brain Spinal cord Nerves Nerve cells = neurons hypothalamus Controls all other systems Hypothalamus – maintains homeostasis by working with all systems
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Interactions with Other Systems
Function Diagram Major Organs Interactions with Other Systems Muscular Allows for movement by contracting Cardiac muscle Smooth muscle Skeletal muscle tendons 1. w/skeletal – allow movement 2. w/digestive – allow organs to contract to push food through 3. w/respiratory – diaphragm controls breathing 4. w/circulatory – controls pumping of blood (heart) 5. w/nervous – controls all muscle contractions Skeletal 1. protects organs 2. provides shape, support 3. stores materials (fats, minerals) 4. produces blood cells 5. Allows movement Bones Cartilage ligaments 1. w/muscular – allow 2. w/circulatory – produce blood cells 3. w/immune – produce white blood cells 4. w/circulatory and respiratory – protects it’s organs
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