Cells Anatomy & Physiology

Cells vary in SIZE and STRUCTURE Depends on what they do

Types of Cells (p. 62)

Cytology = the study of cells All Animal Cells have 3 main parts Nucleus Cytoplasm (cytosol) Cell Membrane

What do you think situs inversus is? Mackenzie, at 4 years old, was diagnosed with pneumonia. Her parents were worried, it seemed that Mackenzie was always sick. She always had a runny nose and had frequent ear infections. The diagnosis of pneumonia also revealed something else - Mackenzie had a condition known as situs inversus. What do you think situs inversus is? 2. How might Mackenzie’s condition be related to cell disfunction? This mini case is based on a real person (Source), images are stock images from morguefile.com

Lipid bilayer (phospholipids) make up the membrane with proteins embedded to help regulate what comes across the membrane; Fluid Mosaic Model

Plasma membrane Functions: Physical isolation Regulates exchange Cell Membrane is selectively permeable Receptor sites Structural support

Membrane Junctions (p. 67) Tight junctions- tightly fused membrane (barrier) ex. intestinal lining Desmosomes- hold adjacent cells together (like velcro) ex. skin Gap junctions- membrane channels that join cytoplasm of 2 cells Allows- 1.) cell-to- cell passage & 2.) nonstop travelling of electrical impulses ex. heart

Given Mackenzie’s history of illness, sniffles, and ear infections, doctors wanted to rule out cystic fibrosis. A simple “sweat test” is used to diagnose CF. Examine the image. Why is CF considered a disorder related to the cell membrane. Could CF have caused Mackenzie’s symptoms? The sweat test showed that Mackenzie did not have extra chloride in her sweat. Does this mean that she does not have CF? Could there be another cause for Mackenzie’s frequent infections?

The cytoplasm (cytosol) is the area between the nucleus and the membrane. Many of the cell’s metabolic reactions occur in this area. Do you remember what metabolism is?

ORGANELLES-  "little organs" within the cell that perform specific functions The nucleus is to the cell what the __________is to a person. The cell membrane is to a cell what the ________ is to a person.

NUCLEUS - (the “brain” of the cell) Directs cell activities (the “brain” of the cell) Contains genetic information (DNA) in the form of chromatin Also contains a nucleolus – makes ribosomes Has tiny pores in the nuclear membrane is where RNA can exit the nucleus

ENDOPLASMIC RETICULUM Transport system; canals and channels that connect membrane to nucleus and to organelles within the cell Function = transport system Smooth ER (lipid synthesis) Rough ER (contains ribosomes for protein manufacture)

Golgi Apparatus Flattened membranes; Function = package and delivery of proteins produced by the ribosomes Proteins are exported in vesicles

Mitochondria ( The “powerhouse” of the cell ) Chemical energy from food is converted to a useable form (ATP) -- process is called Cellular Respiration What does respiration have to do with metabolism?

Lysosomes - contain digestive enzymes to break down substances (“suicide sac”) Enzymes break down substances in the cell, such as food or worn out cell parts, even bacteria. Remember the video on how beans become farts? What is the enzyme in this image and how do you know? What organ is your body is most like the lysosome?

Lysosomes Peroxisomes * contain digestive enzymes to break down substances Peroxisomes -Detoxification-contain enzymes catalase & peroxidase to breakdown H2O2 (toxic to body) -Lipid metabolism

Centrosome – two cylinders, centrioles, that sit perpendicular During cell division, the centrioles separate and form a spindle. The spindle moves chromosomes during cell division so that each new cell gets the proper number.

CYTOSKELETON made of microfilaments and microtubules which maintain shape and functions in movement

Flagella- long-whip-like projections used for movement

Cilia-small hair-like projections used for movement

Doctors wanted to test Mackenzie for a disorder called “PRIMARY CILIARY DYSKINESIA” This disorder causes cells to not create normal cilia. Cells scraped from the sinuses showed an irregularity in Mackenzie’s cilia. What is different about this cilia? Why would problems with cilia cause pneumonia, ear infections, and a constant runny nose?

What about the situs inversus? Mackenzie can live with PCD, but she will always have a cough and deal with lung and ear infections. What about the situs inversus? Doctors have warned her parents that when she gets older, she may have trouble conceiving a child and is at risk for an ECTOPIC pregnancy. What role does cilia play in reproduction? It is believed that the motion of cilia may play a part in determining the placement of organs within the thoracic and abdominal cavities. In the absence of ciliary motion, organ placement becomes a random event, giving each affected embryo a 50/50 chance of having typical or atypical placement.

1. What part of the cell is most like the stomach? More analogies 1. What part of the cell is most like the stomach? 2. What part of the cell is most like your circulatory system? 3. What part of the cell is most like your brain? 4. What part of the cell is most like your bones? 5. What part of the cell is most like your skin? Super Difficult Bonus Question Which part of the cell do you think is the most responsible for maintaining homeostasis? subjective question, could be either the cell membrane or the mitochondria