bio unit

Cytoplasm

- Not an organelle, but is in both plant and animal cells

- Composed of water and other dissolved substances

- All internal organelles are suspended in it and can move around

- Chemical reactions take place here

Cell membrane

- Plant and animals

- Double layer (phospholipid layer)

- Regulates what enters and leaves the cell

- Semi-permeable (small molecules such as water and oxygen can pass by easily, larger molecules cannot)

Nucleus

- Plants and animals

- Organelle that contains genetic information controlling cell activities

- surrounded by a porous nuclear envelope

- chromosomes store DNA which contains genetic information

- Nucleolus at its core that produces ribosomes

Mitochondria

- Plants and animals

- Powerhouse of the cell

- Converts glucose into energy through cellular respiration

- Muscle cells will have more mitochondria than fat cells

Endoplasmic Reticulum

- Plants and animals

- The transportation system within the cell

- Extends from nucleus to cell membrane

- Assists in the production and transportation of proteins and hormones

- Can be smooth or rough depending on whether it is coated in ribosomes

Golgi Apparatus

- Plants and animals

- Packaging centre of the cell

- Processes and packages proteins and fats to be exported from the cell

- Creates secretes and mucus

- Cells, such as intestine cells, that secrete mucus must have many golgi bodies

Vacuole

- Plants and animals

- Fluid or solid filled sacs surrounded by a membrane

- Many functions including maintaining pressure within the cell (plants), isolating wastes, etc.

- In animals, vacuoles can be found in the cell. In plants, one large central vacuole dominates the cell

Ribosome

- Plants and animals

- Composed of proteins and RNAs

Main function is to help with building proteins in cells

Cytoskeleton

- Plants and animals

- Structure that provides shape and organization to the cells

- helps with cell division and movement

Lysosomes

- ANIMALS ONLY

- Membrane-bound organelle that contains enzymes

- Destroys thing that do not belong to the cell/need to be removed

- acts like the digestive system of the cell

Centrosomes

- ANIMALS ONLY

- An organelle that contains a pair of centrioles arranged at right angles

- Critical structure during cell division

Chloroplast

- PLANTS ONLY

- Membrane-bound organelle that contains a green pigment known as chlorophyll

- Helps plants with photosynthesis

Cell wall

- PLANTS ONLY

- Located outside the cell membrane

- Porous, but rigid structure that supports and protects plant cells

- Made of cellulose

Diffusion

The movement of a solute from high to low concentration

- All molecules move freely

- Will reach equilibrium

Osmosis

The movement of a solvent across a semi-permeable membrane

- All molecules move freely

- Will reach equilibrium

Solute

A substance that is dissolved in a solution.

Solvent

A liquid substance capable of dissolving other substances (typically water)

G1

Cell growth

Synthesis

DNA duplicates

G2

Cell prepares to divide

Prophase

- Nucleus and nucleolus break down

- Chromatin form into chromosomes

- Centrosomes that were duplicated move to opposite ends of the cell

- Microtubules extend from centrosomes to form spindle fibres

Metaphase

- Chromosomes line up in the middle

- Spindle fibres from each centrosome attach to the centromere

Anaphase

- chromatids get separated

- the cell elongates

- the chromatids (now individual chromosomes) are pulled towards the centrosomes at opposite poles by spindle fibres (so the cell can be divided into two and both sides can have the chromatids)

Telophase

- The final phase of mitosis

- The nuclear membrane reforms around the daughter chromosomes

- Daughter chromosomes stretch out to become chromatin

- Spindle fibres break down

- Two nuclei are now visible

- Cells are pinched down in shape

Cytokenisis

- The last phase of the cycle

- Cell splits into two daughter cells

- Pinches down at the cytoplasm

- Cell then restarts the cycle (enters interphase again)

Mitosis in plant cells

- nuclear membrane helps signal spindle development

- During telophase, plant cells divide by producing a cell plate down the middle instead of pinching, which develops into a new cell wall

Stem cells

cells that can develop into other types of cells. They can renew themselves by dividing, even after being inactive for a long time.

undifferentiated cell

cells such as stem cells that can become any cell

Differentiated cell

cells such as nerve cells because they have already developed into a certain type of cell with a specific function and role

embryonic stem cells

These stem cells are totipotent and are found in developing embryos. They can develop into any type of cell

adult stem cells

undifferentiated cells found among differentiated cells in a tissue or organ

stem cell therapy

using stem cells to regenerate or treat the human body

It can be used to treat a variety of diseases including heart disease, diabetes, and spinal cord injury. For example, if someone's heart tissue is damaged, doctors can stimulate tissue growth by transplanting lab grown stem cells into the person's heart, allowing the heart tissue to renew itself

How are stem cells used in drug development

Stem cells are used in drug development through the use of iPS cells. Through this, scientists can reprogram these cells to mimic cancer cells, allowing them to test various anticancer drugs on them.

(iPS cells are genetically reprogrammed cells that have the potential to turn into different cells within the body.)

does stem cell therapy currently work?

No, most stem cell therapy is still at the theoretical stage rather than at the commercial stage

ethical issues with stem cell research

the use of human embryos in medical research, the usage of human biological materials, and the potential for tumour development

Telomeres

- Telomeres are regions of DNA located at the end of each chromosome.

- They protect the chromosomes from damage during cell division

- They get shorter with each cell division, and cells will stop dividing altogether once they get too short.

Aging genes

Aging genes are hundreds of genes that are directly linked to development and aging. These genes related to cellular function and maintenance stop functioning as we grow older.

Cancer

a group of diseases in which cells grow and divide out of control. This is because of a change in the DNA, leading to failed checkpoints during the cell cycle.

Tumour

a mass of cells that continue to grow and divide without any obvious function in the body.

benign tumor

Benign tumour does not affect surrounding tissues and is not considered cancerous. They may, however, physically crowd surrounding cells and tissues

Malignant tumour

Malignant tumour interferes with the functioning of surrounding cells and tissues and is considered cancerous.

Hereditary cancer

Hereditary cancer occurs when a gene mutation that increases cancer risk is passed down from a parent to a child.

environmental cancer

cancer caused by carcinogens (environmental factors that cause cancer. Well-known carcinogens include tobacco smoke; radiation, such as X-rays and UV rays from tanning beds and sunlight)

Centromere location + aging

centromeres sometimes do not align properly during metaphase due to missing or malfunctioning proteins.

Metastasis

Metastasis is when cancer cells break away from the primary tumour and spread to a different part of the body

What causes cancer

Cancer is caused by DNA mutations, which can either cause cell death or continue to grow and divide. Carcinogens, such as tobacco smoke and radiation, can cause cancer, while hereditary mutations, like those causing breast and colon cancer, are passed down through generations.

Cancer screening

Cancer screening is checking for cancer even if there are no symptoms. Those with hereditary genes will prefer to do a genetic screening

Pap test

Women may do a Pap test by taking a sample of cervical cells to check for cervical cancer

PSA test

Men may do a self-examination to check for prostate cancer by doing a PSA test (blood test).

ABCD of moles

The ABCD of moles is a self-examination method to identify suspicious moles. It involves asymmetry, border, color, diameter, and sometimes evolution. Regular moles are symmetrical, have a circular border, have one color, are small, and do not change significantly over time.

How to reduce the risk of cancer

To reduce cancer risk, adopt lifestyle choices like avoiding tobacco smoke, exercising, and consuming healthy diets rich in superfoods like broccoli, tomatoes, and carrots, which are high in vitamins, minerals, and antioxidants. Antioxidants protect your body against free radicals (atoms or molecules with unpaired electrons), which can cause cancer and other health problems.

How is cancer diagnosed

- Endoscopy: a cable attached with a camera can be inserted into your body

- X-ray: using electromagnetic radiation to check in the insides of your body

- Ultrasound: Using high-frequency sound waves to create digital images

- CT scanning: X-ray done at different angles for a more complete picture

- MRI: using radio waves and a magnetic field to produce a 3D model.

If the images or models show abnormalities, then the next step is to take a sample. This can include a blood test or a biopsy where the cancer cells taken from the sample are viewed under the microscope to determine if they are benign or malignant.

cancer treatments

Cancer treatments include surgery for simple tumours, chemotherapy for slowing down cell division, radiation treatment for targeted tumour damage, and biophotonics for early detection and targeted treatment. Surgery is the preferred method for accessible tumours, while chemotherapy involves drugs to prevent cell division.

potency

A cell's ability differentiate into other cells

totipotency

ability to give rise to any type of cell

Found in embryos

pluripotency

ability to give rise to many types of cells

Why do cells divide

1. to grow

2. to repair

3. to reproduce

cell theory

1. All living organisms are made up of one or more cells

2. the cell is the simplest unit that can carry out all life processes

3. all cells come from pre-existing cells.

Prokayrotes

Prokaryotic cells are found within the bacteria and archaea domains Smaller, unicellular organisms with NO membrane-bound organelles

Eukaryote

Eukaryotic cells are found within the eukarya domain (i.e., plants, animals, fungi, protists, etc.) Larger, mostly multicellular organisms with membrane-bound organelles DNA in nucleus

Cell specialization

cells that can perform a specific function (i.e. muscle cells to help you move, red blood cells to carry oxygen, and so on)

The digestive system

Organ systems that takes in, breaks up, digests and excretes waste

• 4 stages of digestive process:

  • Ingestion (takes in)

  • Digestion (breaks down)

  • Absorption (absorbs)

  • Elimination (expels)

Oral Cavity

• A.k.a. Mouth

• Entry of foods and liquids (ingestion)

• Site of mechanical and chemical digestion

  • Mechanical - chewing

  • Chemical - salivaS

Salivary glands

• 3 pairs of glands:

  • Sublingual glands (under tongue)

  • Submandibular glands (under jaw)

  • Parotid glands (by cheeks)

• Contains enzymes to help break down food chemically

Esophagus

• Tube that connects your oral cavity with your stomach

• Moves food to the stomach through peristalsis

• Esophagus inner wall lined with mucus

• Wall also contains circular and longitudinal muscles that move involuntarily (you have no control over them)

Stomach

• Organ that holds food for further digestion

  • Mechanical - churning of food

  • Chemical - breakdown using acids and enzymes

• Acids and enzymes produced by cells in stomach lining

• Stomach wall contains muscles to help with churning

Liver

• Not part of digestive tract but helps with digestion

• Produces and secretes bile (greenish fluid that helps break down fats)

• Can also filter wastes from your blood

Gallbladder

• Connects to the liver through a bile duct

• Stores and concentrates bile produced by the liver

• Too much cholesterol or salts in the bile will cause the formation of gallstones

Pancreas

• Produces and secretes enzymes that breaks down various types of macromolecules

• Pancreatic duct carries these enzymes into the small intestine

Small intestine

• Main site for absorption of nutrients

• Chemical digestion also occurs here (recall bile and pancreas secretions)

• Mucus secreted by goblet cells

• Intestinal wall lined with cells containing villi and microvilli (hair-like structures) to maximize absorption

Appendix

• Finger-like structure located at the start of the large intestine

• Function is largely unknown but speculated to house “good bacteria” for your gut

• Needs to be removed if infected

Large intestine

• A.k.a. colon

• Main site of water and salt absorption from the digested food

• Digested food will slowly turn into stools as they traverse through the colon

Rectum

• Main function is to hold stools that passed through the large intestine

• As the rectum fills up, signal is sent to the brain for the waste to be expelled

Anus

• Main function is to expel waste from the body

• Anal sphincter prevents stools in the bowels from leaking out when contracted

• Sphincter relaxes during bowel movements

Problems with the digestive system

• Stomach ulcer

  • hole in the stomach lining, caused by bacteria

• GERD (acid reflux)

• Celiac disease

The respiratory system

• Provides oxygen for the body and allows carbon dioxide to leave the body

• Works closely with the circulatory system

• Also closely intertwined with the digestive system

types of respiratory system

1. direct gas exchange

   1. small organisms such as protists using their cell surface

2. gills

   1. fish

3. skins

   1. amphibians

4. tracheal system

   1. insects

5. lungs

nasal cavity

• Point of entry for oxygen into the body

• Other functions include smelling and protecting your airways from airborne debris

oral cavity

• Oxygen can also enter your body through your mouth

• Parts of the digestive system shares the same tract as the respiratory system

pharnyx

• A.k.a. throat

• Connects your oral cavity and nasal cavity

• Moves air to the larynx

• Moves food to the esophagus

larnyx

• A.k.a. Voice box

• Prevents food from getting into the respiratory system

• Epiglottis helps cover the opening of the larynx

• Creates sound to help with oral communication

epiglottis

• Flap of cartilage located by the larynx that can open or close the respiratory tract

• Open when you are breathing

• Closed when you are eating or drinking

• You cannot breathe and eat/drink at the same time! (otherwise, you will choke)

trachea

• A.k.a. Windpipe

• Brings air to the lungs

• Made up of rings of cartilage connected by ligaments and muscles

• Branches off into two bronchi

Bronchi/Bronchioles

• Bronchi (sing. bronchus) are the larger branches

• Bronchioles are the smaller branches

• Both work to transport oxygen to the alveoli throughout the lungs

Lungs

• Two lungs in humans

• Contain sites for gas exchange and protect the structures within

• Made up of connective tissue

Alveoli

• Small air sacs at the end of bronchioles with lots of capillaries

• Gas exchange occurs here (O₂ gets absorbed by the bloodstream and CO₂ gets expelled)

Diaphragm

• A layer of muscle located beneath the lungs

• Controls breathing along with other muscles found around the rib cage

Breathing

• Breathing in (inhalation): external intercostal muscles and diaphragm contract (i.e. moves down), enlarging the space for lungs to expand

• Breathing out (exhalation): external intercostal muscles and diaphragm relax (i.e. moves up), shrinking the space for lungs to contract

Problems with the respiratory system

• tuberculosis

  • infectious disease

• coronavirus

• covid-19

the immune system

• Network of organs, cells, and proteins that protect your body from diseases

• Protects your body from bacteria and viruses

• Includes surface barriers and the immune response system

surface barriers

• Skin - first protection against pathogens

• Mucus layer/hair - traps pathogens that may have entered through the nose or mouth

• Stomach acid - pathogens entering the stomach will have to survive acidic conditions

immune response

• White blood cells are responsible for the fight against pathogens

• Two types of response:

  • Phagocytosis (eating of pathogen)

  • Antibodies

phagocytosis

• Pathogen gets swallowed by the white blood cell through a process called phagocytosis

• Cell membrane wraps around the pathogen (i.e. forming a  vacuole)

• Afterwards, the lysosomes will dissolve (digest) the intruder

antibodies

• Certain white blood cells will produce antibodies, which will recognize specific pathogens

• Antibodies may “cover” the pathogen to prevent infection, or mark the pathogen for other white blood cells to ingest

vaccines

• Contracting the pathogen to create antibodies and build immunity can be dangerous

• Traditional vaccines contain weakened pathogens that your body can fight off and create antibodies

• Booster doses are given when immunity wanes

the endocrine system

• Creates and releases hormones (chemical substances that signal/stimulate various parts of the body)

• Consists of various tissues and glands

pineal gland

• Regulates the circadian rhythm (i.e. biological clock) within the body

• Releases melatonin that helps with sleep

hypothalamus

• Maintains homeostasis (stability of conditions) within the body

• For example, body temperature is kept around 37^oC

pituitary gland

• “Master gland”

• Controls all the other glands in the endocrine system

• Regulates growth, metabolism, reproduction, etc.

thyroid gland

• Located below the larynx

• Regulates metabolism and growth with the body