Biology biochem

polar covalent bond

A chemical bond in which electrons are not shared equally

Based on what you know about plant and animals cells, which of the following events are most likely to have occurred?

A host cell that gave rise to modern plants ingested both aerobic and photoautotrophic bacteria, while a host cell that gave rise to modern animals ingested aerobic bacteria only.

Why is it possible for humans to digest food that contains starch, but not cellulose.

Amylase can digest 1,4 linkage of glucose found in starch whereas it cannot digest the linkage of glucose found in cellulose.

Discuss how buffers help prevent drastic swings in pH.

Buffers absorb excess hydrogen and hydroxide ions to prevent increases or decrease in pH. An example is the bicarbonate system in human body.

What property of carbon makes it essential for organic life?

Carbon can form up to four covalent bonds, allowing it to form long chains

How many neutrons do carbon-12 and carbon-13 have, respectively?

Carbon-12 contains 66 neutrons while carbon-13 contains 77 neutrons.

What property of carboxyl makes carboxyl containing molecules hydrophilic? Which macromolecules contain carboxyl?

Carboxyl groups release H+, making its parent molecule hydrophilic. It is found in phospholipids and triglycerides.

description of the polarity of water

Hydrogen ends are positive, Oxygen end is positive

Why can some insects walk on water?

Insects can walk on water because of its high surface tension.

You have been identifying the sequence of a segment of a protein. The sequence to date is: leucine-methionine-tyrosine-alanine-glutamine-lysine-glutamate. You insert arginine between the leucine and methionine. What effect would this have on the segment?

Inserting arginine places a positively charged amino acid in a portion that is non-polar, creating the possibility of a hydrogen bond in this area.

What makes ionic bonds different from covalent bonds?

Ionic bond involves the transfer of electrons whereas covalent bond involves the sharing of electrons.

One of the risks for people with diabetes is diabetic ketoacidosis, a build-up of acid in the blood stream. Explain why this is dangerous to humans.

One of the risks for people with diabetes is diabetic ketoacidosis, a build-up of acid in the blood stream. Explain why this is dangerous to humans.

What are the differences in the way lipids are found or function in plants and animals?

Plants store starch and do not have bile salts whereas animals store triglycerides and have bile salts.

What categories of amino acids would you expect to find on the surface of a soluble protein and which would you expect to find in the interior? List some examples for each part of the answer.

Polar and charged amino acids will be found on the surface whereas non-polar in the interior.

The word hydrolysis is defined as the lysis of water. How does this apply to polymers?

Polymers break by separating water into hydrogen and hydroxyl group that are added to the monomers.

What are the differences between saturated and unsaturated fats?

Saturated fats are solid at room temperature and unsaturated fats are liquid at room temperature

Animals cannot digest cellulose due to the type of bonding between the glucose monomers. The glucose monomers are there for an energy source but are unattainable. Yet ruminants such as cows and sheep, and termites eat cellulose in the form of grasses and wood. How do they do it?

Specialized bacteria and protists are found in the digestive tracts of these animals making cellulase that results in cellulose breakdown.

What type of compound functions in hormone production, contributes to membrane flexibility, and is the starting molecule for bile salts?

Steroids serve in the hormone production and cholesterol contributes to membrane flexibility, and precursor for bile salt production.

polar

Substances that can dissolve easily in water

Predict what happens if even one amino acid is substituted for another in a polypeptide and provide a specific example.

The amino acid may not show any significant effect the protein structure and function or it may have a significant effect as in the case of sickle cell hemoglobin.

Explain how the nucleus and the endomembrane system work together for protein synthesis.

The endomembrane system processes and ships proteins specified by the nucleus. In the nucleus, DNA is used to make RNA which exits the nucleus and enters the cytoplasm of the cell. The ribosomes on the rough ER use the RNA to create the different types of protein needed by the body.

Fiber is not really a nutrient, because it passes through our body undigested. Explain why fiber cannot be digested and why it is important to our diet.

The enzymes required to digest cellulose are not produced in human body; undigested fiber adds bulk to the food easing bowel movements.

In the context of cell biology, what do we mean by "form follows function?" What are at least two examples of this concept?

The form of the structure is dictated by its function. For example, the arms of humans and the wings of bats serve different functions, and thus their forms are adapted to those functions.

What happens to the proteins that are synthesized on free ribosomes in the cytoplasm? Do they go through the Golgi apparatus?

The proteins do not go through the Golgi apparatus and remain free in the cytosol.

If a peripheral membrane protein were synthesized inside the lumen of the ER, would it end up on the inside or outside of the plasma membrane?

The vesicle travels from the Golgi to the plasma membrane to release the protein outside.

The fatty acids of triglycerides are classified as saturated, unsaturated, or trans fats. What is it about the structure of these compounds that give them their physical characteristics?

Unsaturated fats and trans fats have some double bonded carbon atoms, while saturated fats do not.

When the temperature of liquid water is reduced, water freezes and becomes less dense. This is a property not seen in most other liquids. Ice floats on liquid water because it is less dense. What molecular property of water allows for this phenomenon?

When water cools, hydrogen bonds between hydrogen atoms push water molecules further apart.

closely related properties of water

adhesion and surface tension

surface tenstion

allows certain bugs to walk on water

which functional group makes molecules more basic

amino

if a substance has a pH of 7.9 it is

basic

covalent

bonds that hold the oxygen and hydrogen atoms within a water molecule

The pH of a solution is determined by

concentration of hydrogen ions

if a hydrogen ion concentration of liquid increases the pH value:

decreases

Neutrons

different isotopes of an element have different

Which of the following bodily process would most likely be hindered by a lack of water in the body?

digestion

Why is carbon special?

due to it's electron structure it can form 4 covalent bonds

these molecules are...

enantiomers

Hydrogen Bonds

for when individual water molecules bind together

These molecules are _____.

geometric isomers

Macrophages ingest and digest many pathogens. Which organelle plays a major role in the activity of macrophages?

lysosome

acidic

pH below 7

polarity

property of water that allows cohesion of water molecules

Why can water be a good insulator within the body of warm-blooded animals?

specific heat capacity

Buffers

substances that minimize changes in the concentration of hydrogen and hydroxide ions

specific heat capacity

temperature is more stable near a body of water due to this water property

chemical reaction

the breaking of chemical bonds leading to changes in composition of matter

You are looking at a sample under a light microscope and observe a new type of cell. You come to the conclusion that it is a bacterium and not a eukaryotic cell. What would you observe to come to this conclusion?

the cell does not have a nucleus

Sweating cools people because:

water molecules absorb heat energy from body

The unique properties of water are important in biological processes. For the following three properties of water, define the property and give one example of how the property affects living organisms: 1. cohesion 2. adhesion 3. high heat of vaporization

Cohesion is the attraction between the water molecules, which helps create surface tension. Insects can walk on water because of cohesion. Adhesion is the attraction between water molecules and other molecules. Water moving up from the roots of plants to the leaves as a result of capillary action is because of adhesion. Heat of vaporization is the amount of energy required to convert liquid into gas. This property helps humans maintain homeostasis of body temperature by evaporation.

What are the structural differences between DNA and RNA?

DNA contains deoxyribose and thymine while RNA contains ribose and uracil.

What are three examples of how the characteristics of water are important in maintaining life?

First, the lower density of water as a solid versus a liquid allows ice to float, forming an insulating surface layer for aquatic life. Second, the high specific heat capacity of water insulates aquatic life or bodily fluids from temperature changes. Third, the high heat of vaporization of water allows animals to cool themselves by sweating.

Why are hydrogen bonds and van der Waals interactions necessary for cells?

Hydrogen bonds and van der Waals interactions form weak associations between molecules, providing the necessary shape and structure for DNA to function in the body.

Inhibitors of microtubule assembly, vinblastine for example, are used for cancer chemotherapy. How does an inhibitor of microtubule assembly affect cancerous cells?

The inhibitors restrict the separation of chromosomes, thereby stopping cell division.

Describe the pH scale and how it relates to living systems. Give an example of how drastic pH changes are prevented in living systems.

The pH scale ranges from 0 to 14, where anything below 7 is acidic and above 7 is alkaline. The bicarbonate system in the human body buffers the blood.