Biology
Biology is the study of life; in this unit we talked about cells (types, what they're made up of and specialization), the cell cycle, 3 organ system, and the interactions between the different systems.
Describing Cells and Their Importance
Cells-What are they?
The are the smallest unit which can perform all functions of a living thing
Types of Cells
Eukaryotic Cells
Cells which have a nucleus and membrane bound organelles;
the chromatin/DNA in this type of cell is located within a membrane bound nucleus
Examples of Eukaryotic Cells
Animal Cells
Animal cells make up animals including humans
Here is a diagram of an animal cell:
Organelles of an animal cell:
Nucleus
Mitochondria
Lysosome
Ribosome
Cytoplasm
Cell Membrane
Golgi Apparatus
Endoplasmic Reticulum
Key Organelle(s):Mitochondria & Nucleus
Mitochondria
The mitochondria is the powerhouse of a cell; it (metabolizes nutrients &) helps produce energy which can be used by the cell to function through a process called cellular respiration
Cellular Respiration
Cellular Respiration is the process of converting nutrients into energy that can be used by the cell called ATP
Nucleus
The nucleus is the most crucial organelle of the cell; it contains DNA and acts like the brain of the cell
What is DNA (deoxyribonucleic acid)?
DNA is the material within a cell which contains coded instructions for all cell activities. When cells go through cell division the instructions within the DNA is also duplicated
Forms of DNA
During different stages DNA can take different forms;
it can be chromatin, chromosomes, or chromatids
Chromatin
Spaghetti shaped structures inside the nucleus of cells which contains the DNA
*This form of chromatin is seen during interphase
Chromosomes
Condesed form of chromatin (meaning they also contain genetic info) which resembles an X that is only visible during the beginning phases of mitosis
Chromatids
A chromosome is essentially 2 chromatids connected by centomer; the chromatids resemble a V. During anaphase the chromosomes are split (seperating the 2 chromatids)
Plant Cells
Plant cells make up the plants around us including trees, fruits vegatables, flowers etc.
Here is a diagram of an plant cell:
Organelles in a plant cell:
Central Vacuole
Chloraplast
Endoplasmic Reticulum
Golgi Body
Ribosomes
Cytoplasm
Cell Wall
Mitochondria
Nucleus
Key Organelle(s): chloroplast
Chloroplast
Chlorplast is an organelle exclusive to plant cells; they conert sunlight and water into nutrients for the cell through a process called photosynthesis
Photosynthesis
Photosynthesis is the process of converting sunlight, water, and carbon dioxide into nutrients the cell can actually use.
Below is the chemical equation for photesynthesis
Prokaryotic Cells
Cells which do not have a nucleus or membrane bound organelle; the chromatin within this type of cell is not enveloped in a nucleus
Example of a Prokaryotic Cells
Bacteria
Here is an image of an E.coli cell:
Cell Cycle
-The cell cycle is essentially life cycle
-There are 3 main stages within this cycle; interphase, mitosis and cytokinsis
-When cells complete the entire the cell cycle 2 daughter cells form which are identical to the parent cell
Interphase
-Cells spend the most time here (~90%) as they are growing, developing, performing cellular respiration, and consuming nutrients
-There are 4 substages within interphase; G1, G0, S G2
G1 (Gap 1)
Most cells spend their time in this sub stage as this is where the cell grow and develop
S (Synthesis
At this stage, the DNA contained in the chromatin of the parent cell is divided into 2 (or duplicated) before entering mitosis
G2 (Gap 2)
At this stage, the cell prepares to divide so organelles are duplicated
G0 (dormant stage)
*Some cells may skip S phase and G2 phase and directly go to G0 phase from G1 phase
-At this stage, cells are alive and continue to metabolize BUT they do not divide or grow in size (since it skips the S stage and DNA isn’’t replicated these cells cannot be replaced if they become damaged
Cell Division& its Importance
Cell division is the process of how cells duplicate and crete new cells
Importance of Cell Division:
-Multi-cellular organisms grow steadily because of cell division; one cell can not function efficiently if it gets too big
-Tissues repair and regenrate through cell division; damaged tissues ust be repaired to keep organisms alive
-Reproduction (both sexual and asexual) occurs through cell division
2 main phases of cell division
Mitosis
-This is the stage where the nucleus (which contains DNA) is replicating and dividing
-There are 4 substages of mitosis: prophase, metaphase, anaphase, and telophase
Prophase (at this stage...)
- Chromatin (long spaghetti like structures) condense into chromosomes (which look like an X)
-Nuclear membrane begins to dissolve
*Chromosomes are identical sister chromatids (look like a v) held together by centomere
Metaphase (at this stage...)
-Nuclear membrane dissolves completely
-Chromosomes line up at the centre of the cell
Spindle fibers attach to the centomere of every chromosome
Anaphase(at this stage...)
-Spindle fibres (pull to) split chromosomes split into halves and are subsequently moved to opposite poles of the cell causing sister chromatids become daughter chromosome
Telophase (at this stage...)
-Spindle fibres break down
-Chromosomes become chromatin again
-New nuclear membranes begin to form resulting in 2 nuclei
Cytokinesis
-This is the last stage of cell division where the cytoplasm is divided (distribuing the organelles to the 2 separate sides)
-For animal cells, the cell membrane is pinched by inward (forming a cleavage furrow) finally producing 2 identical daughter cells
-For plant cells, a plate forms across the center of the plant cell forming a new cell wall (thus againn creating 2 identical daughter cells)
Cell Death
Cells may die if they become too damaged to function and divide. Irreparable cell damage may be caused by :physical force, toxic chemicals, or infections caused by a virus.
Cell Apoptosis
This type of death is programmed (meaning it is predetermined by the cell’s genes aka DNA) into the cell when it forms. Moreover, the cell breaks down in an organized manner to produce raw materials other cells can use.
Importance of Cells
They allow organisms to have the characteristics
of a living thing
Functions/Characteristics of a Living Thing
These functions/characteristics are what is required of a substance/thing to be considered living/to have life
What are the characteristics?
Living things must be able to...
Growth
-Grow larger in size and population
Reproduction/Repair
-Repair damage caused by enviroment
-Reproduce to grow/increase/and mainatin population
Adaptibility
-Adapt to changes within their environment or adapt to survive in other enviroments
Metabolization
-Get nutrients from the environment and change that into usable energy
Movement
-Have the ability for the organism itself to move and/or spread its reproductive (/daughter) cells/offspring
Irratability
-Reacts to stressors and stimuli in their respective enviroment
Cellular Structures
All organisms must be made up of cells
Billions of cells come together to form humans; cells are the smallest unit in the hierachy of living things (meaning they are a part of everything more complexer)
Hierachy of Living Things
The of living things is a diagram which shows the simplest components of an organism to the most complex; the hierachy of living things show you the different levels of living things from the smallest components to larger components.
Tissue
A group of specialized cells that perform similar functions
Organ
A complex structure made of various tissues which perform
many specific functions
Ex. The heart is made up of various muscle tissues
Source:http://clipart-library.com/clipart/gTe5aL7yc.htm
Organ System
A system made up of various tissues, organs, and cells which work together to perform a specific function required for the survival of an organism
Ex.The circulatory system is made up of various organs like the heart and blood vessels
Source:https://biologydictionary.net/circulatory-system/
Organism
An object which has all the characterisitics of a living thing; multicellular organism have many organ systems
Ex. Humans (like myself) are an example of multicellular organisms as we have 11 organ systems (e.g circulatory, digestive, respiratory, endocrine, urinary, reproductive, & more)
Cell Theory
A theory used to describe all living things
This theory states:
1)All living things must be composed of at least one cell
2)All cells must come from/be created by pre-existing cells
3)Cells are the basic building block of life
Exploring Cell Specialization
and their Functions
Cell Specialization/Differentiation
Cell differentiation is a specific process which yields specialized cells; basically unspecialized (stem cells) become specialized
Example of Cell Differentiation:
Multipotent stem cells in the bone marrow become red blood cells (RBCs are specialized as they have the responsibilty of transporting oxygen and nutrients toand colecting waste products (i.e CO2) from organs in the body
Specialized Cells
Cells which have a specific or many particular responsibilities and functions which allow the organism to stay alive, be healthy, and fuction effectiently; specialized cells can only make one type of cell as well (the same type they are i.e epithelial cells can only make epithelial cellw)
Examples of Specialized Cells
Epithelial Cells
-When epithelial cells go through cell division they only produce epithelial cells
-Epithelial cells come together and form tissue which protect the the body, help moderate temperature, and secrete mucous
Source:Nelson Science Perspectives 10 Textbook
Stem Cells
Stem cells are essentially unspecialized cells (cells which do not have a specific function) which have the ability to produce specialized cells
Types of Stem Cells
Totipotent Cells
Unspecialized cells which have the ability to produce any/all specialized cells
Pluripotent Cells
Also known as embryonic stem cells which can produce many/most types of specialized cells but not all
Multipotent Cells
Stem cells located in full grown organisms which can only produce specific specialized cells
Human Organ Systems
&Interactions Between
Systems
Organ System
A system made up of various tissues, organs, and cells which work together to perform a specific function required for the survival of an organism
Digestive System
The digestive system is an organ system which allows our bodies to ingest and digest food, absorb essential nutrients, and eliminate waste which is made up of the digestive tract and accessory organs
Parts of the Digestive System:
Digestive Tract:
Mouth
Esophagus
Stomach
Large Intestine
Smal Intestine
Anus
Accessory Organs:
Liver
Pancreas
Gallbladder
Functions of the Digestive System
Ingestion
When food actually enters your system through your mouth
Digestion
Food is broken down to allow for absorption (and ultimately elimination); food can be broken down in two ways
Mechanical Digestion
Food is broken down through physical force
Ex. When you chew your teeth break down food into smaller pieces so you can swallow it
Chemical Digestion
Food is broken down by enzymes and acids produced by the body
Ex.Hydrochloric acid and Pepsin which are chemicals in the stomach which help breakdown food
Absorption
Nutrients from food is absorbed by the intestines into the bloodstream
Elimination
Undigested food and waste is excreted from the body as fecal matter
How does food move through the digestive system?
1)FIrst your teeth chew food. Simaltaneously, saliva from the salivary glland soften the food (and an enzyme within saliva called amalyse breaks down starches) to allow it to go down the esophagus.
2)The esophagus practices somethng called perestasis which is when the muscles of the esophagus contract to push food down.
3)When the food enter the stomach chemicals such as pepsin and hydrochloric acid break down the food. The muscles in the stomach also ontract and churn the food to help with digestion. 3) Next is the small intestine, in the duodenum enzymes from the liver and pancreas help further break down food. The small iintestine helps absorb nutrients from the food.
4)The large intestine has good bacteria which help absorb water, salt, and vitamin K. After the water is absorbed, all waste and undigested food is expelled out of the body as fecal matter
Circulatory System
It is an organ system which transports oxygen (from the lung) and nutrients (obtained through absorption) to other cells within the body and carry away waste products from cells through the bloodstream
Parts of the Circulatory System
Heart
The heart is a muscle which contracts and relaxes to pump blood around the body.
Blood Vessels-structures which transport/help circulate blood
1)Arteries
Thick-walled tube like structures which transport oxygen rich blood/oxygenated blood away from the heart to other parts of the body
2)Veins
Tube like structures (thinner than arteries but thicker than capillaries) which transport deoxygnated blood from the body back to the heart
3)Capillaries
Thin walled vessels which join veins and arteries and allow chemicals to diffuse into the bloodstream (;they pay a key role in absorption and gas exhange
Blood-a type of connective tissue which mainly transports oxygen and nutrients and removes carbon dioxide and waste; it's made of 4 parts:
1)Red Blood Cells
2)White Blood Cells
3)Platelets
4)Plasma
Functions Of the Circulatory System
Flow of Blood
Deoxygenated blood (blood with a higher concentration of CO2 than oxygen) returning from the body enters the right atrium then the right ventricle and travels through the pulmonary artery to the lungs. Oxygenated blood (blood witha higher concentration of oxygen than carbon dioxide) returns to the heart through the pulmonary vein then goes to the left atrium and ventricle and through the aorta from where it gets distributed to the rest of the body. This process repeats everytime your heart beats
How does oxygen get into other organs through the circulatory system?
The oxygen from oxygenated blood diffuses into the organ (as the blood now has a higher concentration of oxygen than the organ) and the excess CO2 diffuses into the blood; this deoxygenated blood is taken back to the heart then lungs (alveoli) where the blood is oxygenated again
Respiratory System
The respiratory system is an organ system which supplies necessary oxygen (to the entire body) and helps expel carbon dioxide (which is a waste product created during cellular respiration by the cells in your body) out of the body
Parts of the Respiratory System:
Trachea
Mouth/Nose
Bronchi
Bronchioles
Lungs
Alveoli
Functions of the Respiratory System
Breathing
Breathing is ultimately alternating the actions of inhaling (breathing in) and exhaling (breathing out)
- When you inhale, oxygen enters through your nose and mouth, your diaphragm flattens (contracts) to allow the volume of the lungs to increase delivering oxygen to the site of gas exchange (alveoli)
-Similarly when you exhale to opposite happens, the lung deflates, the diaphragm relaxes, and CO2 collected in the alveoli is expelled out of the body allowing your diaphragm to relax.
*This process repeats every time you breathe even though you may not know it.
Gas Exchange
Deoxygenated blood from the heart goes to capillaries which surround alveoli. The oxygen in the alvoli (obtained through inhalation) diffuses into the red blood cells (this happens quite easily because they are both thin walled). Simataneously, carbon dioxide from the red blood cells diffuse into the alveoli.
What is diffusion?
This is how nutrients and waste (chemicals) enter and exit a cell; in diffusion materials are always trying to balance out material basically substances from areas with a high concentration move to areas with a lower concentration
How does oxygen get to the alveoli?
1)Oxygen is inhaled through the nose and mouth
2)The oxygen travel down the trachea and divides into bronchi which lead to each lung
3)The oxygen the travels through the small branches called bronchioles and enter the air sacs called alveoli so the oxygen can be used for gas exchange
4) CO2 leaves the body in reverse of how oxygen enters
Comparing Controlled
and Uncontrolled
Cell Division
What is Controlled Cell Division?
Controlled cell division describes cells which oblige to the signals sent by the checkpoint and are divide in a steady manner; they go through interphase and cell division (the cell cycle) at a sufficient rate
Non-Cancerous Cells
Non-cancerous cells are the normal/healthy cell they are the product of controlled cell division; (meaning they divide at a steady rate) normal cells oblige to cell checkpoints and self-destruct (and go through cell apoptosis) when they sense they are too old or damaged to function
What are Cell Checkpoints?
Cell checkpoints are certain points in a cell’s life (during the cell cycle) when proteins determine if a cell is ready for cell division or not ; cell checkpoints act like a toll gate to prevent cell division from happening if DNA is damaged, chromatin is not duplicated during Synthesis , or adequate nutrients is not available for the cell to grow.
What is Uncontrolled Cell Division?
Uncontrolled cell division describes cells which do not conform to the protein signals given by the cell checkpoint; they go through interphase and cell division (the cell cycle) at a rapid rate. The loss of control is caused by random changes in the DNA called mutations.
Cancerous Cells
Cancerous cell are unhealthy/irregular cells which are the product of uncontrolled cell division; these cells do not obey cell checkpoints, do not self-destruct when they are too old/damaged, and divide at a rapid rate forming tumors
Tumors
A tumor is essentially a mass of cells (within an organism with no function) which is the result of uncontrolled cell division (the rapid dividing of cancerous cells); there are 2 types: malignant tumors and benign tumors
Benign Tumor
A benign tumor describes tumors which are localized to a specific place, and are not disruptive (not as much as malignant tumors) though some larger benign tumors can be a physical nuisance to surrounding cells. Usually benign tumors aren't seen as life threatening/immediate life threats.
Malignant Tumor
Malignant tumors are more harmful to an organism/humans as they interfere with surrounding tissues and their respective functions. Malignant tumors tend to grow faster than benign tumors and unlike benign tumors go through metastasis
Metastasis
Metastasis describes cancerous cells from the primary tumor breaking off and forming a secondary tumor elsewhere in the body(they usually move through the blood vessels).
What is Cancer?
A disease which results in uncontrolled cell division
that disrupts the functions of the healthy cells and tissues needed for humans to function
What causes cancer?
Hereditary
Sometimes you could have genetic links whch can make a person more prone to getting cancer. People who have family who have been diagnosed with cancer are likely to get it so they must be actively screened and try to lead a healthy lifestyle and limit exposure to carcinogens.
Viruses
The DNA of a cell can be changed by viruses; therefore cancer is sometimes a long-term effect or symptom of a viral illness
such as HPV (humanpapilomavirus) and Hep. B.
Carcinogens
-They are essentially any chemical or energy that can cause mutations in DNA (after prolonged exposure)
- An example of a carinogen can include tobacco from cigarettes or certain chemials such as BPA from plastic