Cell Structure

Activity : Cell Structure

Individual Work

1. Based on Image given below, fill in the table with the names and functions of the organelles that you are very sure of. Use green to fill in these fields. 

2. Fill in the table with the names and/or function of the organelles that you might be sure of. Use orange to fill in these fields. 

Think-Pair-Share

3. With a friend, discuss with your friend(s) [if you are working in groups of 3] and modify your existing answers. Once again, if both of you are sure,use green in these fields. If you are both somewhat sure, use orange. If you are confused and not sure at all, use red to fill in these fields. 

4. Carry out research and fill up the last column with your research. 

5. Upload the file to your online journal for reference. 

Component	Organelle Name	Description of Organelle	Function	Electron micrograph
A	Nuclear membrane	A membrane that separates the cytoplasm from the nucleolus.	To keep the chromosomes and chromatin within the membrane.	*
B	Nuclear pore	Hole-like structure	Let information of DNA go out to other parts of cell	*
C	Nucleolus	a region in the nucleus where rRNA genes exist and are transcribed	produces ribosomal subunits Contains DNA, which controls the cell’s activities by directing protein synthesis.	*
D	Lysosome	Contain digestive enzymes	Digest excess or worn-out organelles, food particles and engulf bacteria or viruses. Also help repair worn-out plasma membrane. Cell breaks down if lysosome explodes due to autolysis.	*
E	Rough Endoplasmic Reticulum	Isolate and transport proteins synthesised by attached ribosomes.	Proteins might undergo further folding within here	*
F	Smooth Endoplasmic Reticulum	An interconnected network of tubes and vesicles and lacks ribosomes	Involved in the synthesis of proteins, fats, and steroids	*
G	Cytoplasm	Gel-like mixture surrounded by cell membrane	Contains organelles
H	Golgi Apparatus	Works closely with Endoplasmic Reticulum	Primary function is to process and package complex molecules such as proteins and fats that are made by the cell. Brings these products to the surface of the cell where they can be secreted. Other secretions include hormones, antibodies and enzymes.	*
I	Cell Membrane	it is thin, permeable and mostly flexible and stretchable It does not have a fixed shape or size, of which is constantly changing	Partially permeable, allows some substances to move in and out. Compartmentalize. Prevent autolysis.	*
J	Vacuole	Membrane-bound sacs for storage, digestion and waste removal	Vacuoles might store food or any variety of nutrients a cell might need to survive. They can even store waste products so the rest of the cell is protected from contamination. Eventually, those waste products would be secreted from the cell	*
K	Mitochondria	Second largest organelle with unique genetic structure	Energy-producing chemical reactions take place here	*
L	Ribosome	Each cell contains thousands of it, found on endoplasmic reticulum, & floating throughout the cell	Involved in the synthesis of proteins	*

Regulation Of Water In Body

Journal#1 (OBS) 

During OBS, our class experienced a sea and land expedition. Before these 2 expeditions, our instructors were really strict with us about the amount of  water we needed to bring with us for these expeditions. They specifically told us to bring 4L of water as this is the amount of water needed to replenish while exercising. 

However, I did not drink enough water (only about 1 1/2L) despite sweating a lot under the heat. Hence, my body will try to balance the amount of water lost and gained in my blood. 

Homeostasis is the ability of an organism or cell to regulate its internal conditions or to maintain a constant internal environment. These conditions include:
1. Body's water content
2. Body temperature
3. Body's blood sugar level
4. Carbon dioxide level
Homeostasis is maintained by our hormones and nervous system. Hormones are chemicals secreted by glands to travel through bloodstream to targeted organs. These hormones regulate functions of many organs and cells. For instance, the amount of water in our kidneys.


Body's Water Content
It needs to be controlled so as to prevent cells in our body from damaging due to too much water from entering or leaving the cells caused by osmosis. On a daily basis, we gain water by drinking water or consuming food and the production of water through cellular respiration. We lose water through sweating from skin, urination/faeces and evaporation of water vapour we exhale from lungs. However, we need a balance for gain or loss of water in our body.

This balance is achieved by the hormones anti-diuretic hormone (ADH). ADH aids in negative feedback mechanism, a process which maintains the level of water in our blood. As the level of water falls in our blood, the negative feedback will ensure the amount of ADH rises and as the level of water rises in our blood, the negative feedback will release less amount of ADH.

(If We Had Too Little Water)
Caused by: (heat) sweating a lot, not drinking enough water
-Part of brain, hypothalamus, detects too little water in blood
-Sends a signal to pituitary gland to release more ADH
-More ADH travels in blood to kidneys
-Kidneys remove less water from blood (renal tubule reabsorbs more water into blood)
-Less water is to dilute the urine, hence urine is smaller volume and more concentrated
-Person will become thirsty and hence drink more water
-Water level in blood returned to normal

(If We Had Too Much Water)
Caused by: weather is cold and body not losing water through sweat, drinking enough water
-Part of brain, hypothalamus, detects too much water in blood
-Sends a signal to pituitary gland to release less ADH
-Less ADH travels in blood to kidneys
-Kidneys remove more water from blood (renal tubule reabsorbs less water into blood)
-More water is to dilute the urine, hence urine is greater in volume and more dilute
-Water level in blood returned to normal

Factors affecting amount of ADH produced: alcohol (decrease amount of ADH--> greater in volume of dilute urine--> leads to dehydration), ecstasy (reduce amount of ADH--> smaller volume of concentrated urine--> reduce amount of urine produced)


Links:
http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/ourselves/5_staying_in_balance1.shtml
http://www.abpischools.org.uk/page/modules/homeostasis_kidneys/kidneys6.cfm