Biology 102 Lab

Post-LaboratoryDiscussion

EXERCISES 3-7

Millard Uy, M.Sc.UST - College of Science

Department of Biological Sciences

Exercise no. 3 Digestion

Food Biomolecules and Breakdown

- carbohydrates, proteins, lipids, nucleic acids

- physical and chemicaldigestion

- digestion is necessary for the breakdown of the “not readily absorbable” into “readily absorbable”

- source of energy and source of molecular building blocks

Exercise no. 3 Digestion

I. Physical Digestion- gives way for chemical digestion

- starts from the mouth- physical change- in humans and certain animals, this is facilitated by the set of teeth (incisors, canines, premolars, molars).

- Stomach contributes to this, by contracting, churning movements.

Exercise no. 3 DigestionII. Chemical Digestion

Macromolecules Enzyme Precursors FunctionCarbohydrates Amylases,

CellulasesMonosaccharides energy source,

structural component

Proteins Proteases Amino Acids enzymes, structuralcomponents,

antibodies, hormones,Lipids Lipases Fatty acids, Glycerol energy source,

structural components,hormone synthesis

Nucleic Acids Nucleases Nucleotides ATP, cAMP synthesis, coenzyme component

- starts from the mouth- chemical change- facilitated by enzymes and other secretions (e.g. acids)- through enzymatic hydrolysis (opposite of dehydration reaction—for building / synthesis)

Exercise no. 3 DigestionTypes of Chemical Digestion:

1. Absorptive Digestion - exhibited by simple life forms- secretion of digestive enzymes into surrounding medium, and resulting simple nutrients are absorbed.

2. Ingestive Digestion- exhibited by higher life forms- engulf food into vacuoles or digestive tracts where digestion takes place and nondigestiblewastes are excreted.

Digestive Secretions

Site of Digestion

Source of Secretion

Secretion Role in Digestion

Mouth Salivary glandsSalivary glands

AmylaseMucus, Water

Starch into disaccharidesLubricates, dissolves food

Stomach Lining cells

Lining cellsLining cells

HCl

PepsinMucus

Allows pepsin to work, kills bacteria, solubilizes minerals

Proteins into large peptidesProtects stomach

Small Intestine

PancreasPancreasPancreasPancreasPancreasPancreas

LiverLining cells (S.I)Lining cells (S.I)

Sodium bicarbonateAmylasePeptidasesTrypsinChymotrypsinLipases

BilePeptidasesDisaccharidases

Neutralizes acidic chymeStarch into disaccharidesProteins into small peptidesProteins into large peptidesProteins into large peptidesLipids into fatty acids & glycerolEmulsifies lipidsSmall peptides into am. acidsDisaccharides into Mono-

Some Important Digestive Hormones

Hormone Production Stimulus for Production

Effect

Gastrin Stomach Food in mouthThought of FoodDistension of StomachPeptides in Stomach

Stimulates acid secretion by cells in stomach

Secretin

Cholecystokinin

Gastric-inhibitorypeptide

Small intestine

Small intestine

Small intestine

Acid in small intestine

Amino acids, fatty acids in small intestine

Fatty acids and sugars in small intestine

Stimulates bicarbonate production by pancreas in liver, increses bile output

Stimulates secretion of pancreatic enzymes and release of bile

Inhibits stomach movements and release of stomach acid

In the experiment…1. Why iodine? Iodine is yellowish brown Iodine test distinguishes starch from mono-, disaccharides Starch (coiled polymer of glucose) = bluish black = (+) mono-, disaccharide = yellowish brown = (-)

2. “Gargle” solution? w/ salivary amylase Breakdown starch into disaccharides Starch test = some areas with yellowish brown coloration

3. Fresh Pineapple extract vs. Gelatin Protease enzyme vs. Protein = liquefaction

Guide Questions

Explain why pineapple juice is sometimes used as ameat tenderizer.

Protease Enzymes

Guide Questions

How come canned pineapple tidbits / chunks can besafely mixed with gelatin without ever causingliquefaction of the surrounding gelatin medium?

Degraded Enzymes (during processing)

Guide Questions

Briefly differentiate mechanical from chemicaldigestion.

Physical vs. Chemical

Exercise no. 4 Gas Exchange

Key Concepts in Gaseous Exchange:Plants produce O2 (by-product of photosynthesis) using CO2 and H2O Animals produce CO2 and H2O (by-product of cellular respiration) using O2

In the experiment…1. Why Bromothymol blue in Snail-Hydrilla-H2O

setup? Indicator for respiration or photosynthetic activities Originally blue in color Blue (Alkaline) Green (Neutral) Yellow (Acidic) CO2 produced by snails, reacts with H2O in the setup CO2 + H2O = H2CO3 (Carbonic Acid)

2. Why place setups in a well-lighted area? For photosynthesis

Guide Questions

What happened to the mice in the closed chamber,and the other chambers?

two mice = died early plants = survived but wilted mice + plants = survived longer

Guide Questions

What have you observed on the walls of the sealedchambers of mice? What about the chamber wallsof plants, and also of the mouse and plants?

moisture = gases present

Guide Questions

What is the purpose of setting an empty bottle?

control setup

Guide Questions

What happened to the two-snail setup after 5 days?

died = oxygen deprivation

Guide Questions

Why did the organisms in the snail-Hydrilla setupremained alive?

gas exchange

Guide Questions

Explain why the plant alone (Hydrilla) survived?

pond water = dissolved CO2

Exercise no. 5 Diuresis

Key terminologies

Diuretic – substance that increases urine production.Anti-Diuretic – substance that reduces urine production.

Anti-Diuretic Hormone (ADH) – hormone regulated by the hypothalamus (in the brain) that reduces urine production by making the distal and collecting tubules of the kidney more permaeable to water.Pituitary Gland (posterior) – releases ADH as induced by the hypothalamus.

Exercise no. 5 Diuresis

Salt, Exercise and ADH

Certain sensors in the hypotahalamus aresensitive to changes in the saltconcentration of body fluids, particularlythe blood. If, for example, a person issweating and losing large amounts ofwater, the sodium in the blood becomesmore and more concentrated. Thehypothalamus can sense this highconcentration of sodium and it signals theposterior lobe of the pituitary to releaseADH. The ADH is transmitted by the bloodto the kidneys causing the kidney tubules toreabsorb more water into the blood streamto dilute the sodium. As a result of thiseffect, less urine is produced. This actionconserves water in the body.

In the experiment…

1. Why decrease in urine after exercise? ADH stimulation due to loss of water throughperspiration (to dilute salt concentration in blood)

2. Why let a student drink water only? Control setup

Exercise no. 6.1 Internal Transport in PlantsWater Uptake Plants must maintain optimum water.Water, minerals

root hairs rootsroots xylemxylem shoots

Sugarsleaves phloemphloem other organs

Transpiration in leaves (H2O vapor -stomata) is replaced by absorption in roots (root hairs)Key concepts:(1) More stomata + bigger leaf surface =

faster transpiration rate(2) transpiration = “pull” of water

In the experiment…

1. Why decrease of water in burette?Water uptake through the xylem of the stem to theother organs (e.g. leaves)

2. Why inside a well-sealed bell jar? To be able to observe transpiration (In the form ofmoisture / water droplets)

Guide Questions

Note the inner sides of the bell jar. What evidencethat transpiration has occurred?

moisture / water droplets

Exercise no. 6.2 Girdling a Stem

Guide Questions

What are the pores found at the stems that aremainly for aeration?

lenticels

Guide Questions

What do you call the brown cell layers of the bark(outermost)?

cork

Guide Questions

Name the composite tissues that include theconductive cells that transport food, water and othermetabolites.

xylem and phloem

Guide Questions

What is the mersitematic tissue that gives rise tonew conductive cells?

vascular cambium

Exercise no. 7 Agluttination - Immunology

Experiments with blood transfusions have been carried out for hundreds of years, but many patients have died.

In 1901, Karl Landsteiner discovered human blood groups and found that mixing blood from two individuals can lead to blood clumping.

blood clumping is an immunological reaction which occurs when the receiver of a blood transfusion has antibodiesagainst the donor blood cells.

Brief History on Blood Groups

Exercise no. 7 Agluttination - Immunology

The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies.

The antigens are located on the surface of the RBCs and the antibodiesare in the blood plasma.

Individuals have different types and combinations of these molecules.

According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O (null).

Different Blood Groups

Exercise no. 7 Agluttination - ImmunologyBlood Groups

Blood group AIf you belong to the blood group A, you have A antigens on the surface of your RBCs and B antibodies in your blood plasma.

Blood group BIf you belong to the blood group B, you have B antigens on the surface of your RBCs and A antibodies in your blood plasma.

Exercise no. 7 Agluttination - ImmunologyBlood Groups

Blood group ABIf you belong to the blood group AB, you have both A and B antigens on the surface of your RBCs and no A or B antibodies at all in your blood plasma.

Blood group OIf you belong to the blood group O (null), you have neither A or B antigens on the surface of your RBCs but you have both A and B antibodies in your blood plasma.

When RBCs carrying one or both antigens are exposed tothe corresponding antibodies, they agglutinate; that is,clump together. People usually have antibodies againstthose red cell antigens that they lack.

Human RBC before (left) and after (right) adding serumcontaining anti-A antibodies. The agglutination reactionreveals the presence of the A antigen on the surface of thecells.

Concept of Agglutination

Blood transfusions:who can receive blood from whom?

People with blood group O are called "universal donors"

People with blood group AB are called "universal receivers"