Bio 1A Ch 3 Biological Macromolecules

Study Figure 3.5 Classify Glucose, Galactose and Fructose as either an aldose or a ketose.

Glucose and galactose are aldoses. Fructose is a ketose.

What role do electrons play in dehydration synthesis and hydrolysis?

My answer: In a dehydration synthesis reaction, the H+ of one monomer combines w/a hydroxyl group of another monomer, letting go a molecule of water. Thus creating an opening in the outer shells of atoms in the monomers, which can share electrons & form covalent bonds. Book: In a dehydration synthesis reaction, the hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a molecule of water. This creates an opening in the outer shells of atoms in the monomers, which can share electrons and form covalent bonds.

Why is it impossible for humans to digest food that contains cellulose?

My answer: In cellulose there's a beta 1-4 glycosidic linkage that cannot be broken down by the human digestive enzyme. Book: The β 1-4 glycosidic linkage in cellulose cannot be broken down by human digestive enzymes. Herbivores such as cows, koalas, and buffalos are able to digest grass that is rich in cellulose and use it as a food source because bacteria and protists in their digestive systems, especially in the rumen, secrete the enzyme cellulase. Cellulases can break down cellulose into glucose monomers that can be used as an energy source by the animal.

Figure 3.33 . A mutation occurs, and cytosine is replaced with adenine. What impact do you think this will have on the DNA structure?

My answer: The nucleotide Adenine is larger compare to Cytosine & it will not be base pair correctly with the guanine on the opposing strand. This will make the DNA bulge. DNA repair enzymes may recognize this & replace it w/ a right nucleotide. Book: Adenine is larger than cytosine and will not be able to base pair properly with the guanine on the opposing strand. This will cause the DNA to bulge. DNA repair enzymes may recognize the bulge and replace the incorrect nucleotide.

Why have trans fats been banned from some restaurants? How are they created?

My answer: They are ban due to high levels of LDL or bad cholesterol in them. Trans fats are artificially made when hydrogen gas is bubbled through oils to solidify them. Double bonds of cis-conformation in the hydrocarbon chain can convert to double bond in trans configuration. Book: Trans fats are created artificially when hydrogen gas is bubbled through oils to solidify them. The double bonds of the cis conformation in the hydrocarbon chain may be converted to double bonds in the trans configuration. Some restaurants are banning trans fats because they cause higher levels of LDL, or "bad"cholesterol.

Describe the similarities and differences between glycogen and starch.

My answer: They are both polysaccharides. Also, they are the storage form of glucose. Glycogen is stored in animals (in the liver & the muscle cells). starch is stored in the roots, seeds & leaves of plants. There's two different forms of starch unbranched (amylose) & one branched (amylopectin) whereas glycogen is a single type of a highly branched molecule. Book: Glycogen and starch are polysaccharides. They are the storage form of glucose. Glycogen is stored in animals in the liver and in muscle cells, whereas starch is stored in the roots, seeds, and leaves of plants. Starch has two different forms, one unbranched (amylose) and one branched (amylopectin), whereas glycogen is a single type of a highly branched molecule.

Why are biological macromolecules considered organic?

My answer: They are organic b/c they contain carbon. Book: Biological macromolecules are organic because they contain carbon.

Explain at least three functions that lipids serve in plants and/or animals.

My answer: lipids known as fat can be store as energy for animals. Also serve as insulation. Waxes protects the leaves on plants & mammalian fur from being wet. phospholipids & steroids are major components of animal cell membrane as well as plant, fungal & bacterial membrane. Book: Fat serves as a valuable way for animals to store energy. It can also provide insulation. Waxes can protect plant leaves and mammalian fur from getting wet. Phospholipids and steroids are important components of animal cell membranes, as well as plant, fungal, and bacterial membranes.

Explain what happens if even one amino acid is substituted for another in a polypeptide chain. Provide a specific example.

my answer: A change in gene sequence can lead to a different amino acid being added to a polypeptide chain instead of the normal one. This change the protein structure and function. For example, sickle cell anemia, the hemoglobin beta chain has a single amino acid substitution the amino acid glutamic acid in position six is substituted by valine. Due to change, hemoglobin molecules form aggregates, and the disc-shaped red blood cells assume a crescent moon shape, leading to health problems. Book: A change in gene sequence can lead to a different amino acid being added to a polypeptide chain instead of the normal one. This causes a change in protein structure and function. For example, in sickle cell anemia, the hemoglobin β chain has a single amino acid substitution—the amino acid glutamic acid in position six is substituted by valine. Because of this change, hemoglobin molecules form aggregates, and the disc-shaped red blood cells assume a crescent shape, which results in serious health problems.

What are the four types of RNA and how do they function?

my answer: The four types of RNA is messengerRNA, ribosomal RNA, transfer RNA & microRNA. MessengerRNA carries the info from DNA that controls all cellular activities. The mRNA binds to ribosomes that are constructed of proteins & rRNA. tRNA transfers the correct amino acid to the site of protein synthesis, microRNA regulates the availability of mRNA for translation. Book: The four types of RNA are messenger RNA, ribosomal RNA, transfer RNA, and microRNA. Messenger RNA carries the information from the DNA that controls all cellular activities. The mRNA binds to the ribosomes that are constructed of proteins and rRNA, and tRNA transfers the correct amino acid to the site of protein synthesis. microRNA regulates the availability of mRNA for translation.

Describe the differences in the four protein structures.

my answer: the sequence & number of amino acids in a polypeptide chain is primary structure. The local folding of polypeptide in some regions gives rise to the secondary structure of the protein. The three-dimensional structure of a polypeptide is tertiary structure. Some protein are formed by multiple polypeptides known as subunits & the interaction of these subunits form quaternary structure. Book: The sequence and number of amino acids in a polypeptide chain is its primary structure. The local folding of the polypeptide in some regions is the secondary structure of the protein. The three-dimensional structure of a polypeptide is known as its tertiary structure, created in part by chemical interactions such as hydrogen bonds between polar side chains, van der Waals interactions, disulfide linkages, and hydrophobic interactions. Some proteins are formed from multiple polypeptides, also known as subunits, and the interaction of these subunits forms the quaternary structure.

What are the structural differences between RNA and DNA?

my answer:DNA is double stranded whereas RNA is single stranded. DNA nucleotides contains deoxyribose , one of the four nitrogenous bases (A, T, G, & C) & a phosphate group. RNA ribonucleotides contains ribose, one of the four nitrogenous bases (A, U, G, & C) & a phosphate group. Book: DNA has a double-helix structure. The sugar and the phosphate are on the outside of the helix and the nitrogenous bases are in the interior. The monomers of DNA are nucleotides containing deoxyribose, one of the four nitrogenous bases (A, T, G and C), and a phosphate group. RNA is usually single-stranded and is made of ribonucleotides that are linked by phosphodiester linkages. A ribonucleotide contains ribose (the pentose sugar), one of the four nitrogenous bases (A,U, G, and C), and the phosphate group.

An example of a monosaccharide is ________.

A. fructose B. Glucose C.galactose D. all of the above D. all of the above

Lactose is a disaccharide formed by the formation of a _______ bond between glucose and _______.

A. glycosidic; lactose B. glycosidic; galactose C. hydrogen; sucrose D. hydrogen; fructose B. glycosidic; galactose

During the breakdown of polymers, which of the following reactions takes place?

A. hydrolysis B.dehydration C. condensation D. covalent bond A. hydrolysis

Dehydration synthesis leads to formation of

A. monomers B. polymers C. water and polymers D. none of the above C. water and polymers

Cellulose and starch are examples of:

A. monosaccharides B. disaccharides C. lipids D. polysaccharides D. Polysaccharides

The monomers that make up proteins are called ________.

A. nucleotides B. disaccharides C. amino acids D. chaperones C. amino acids

The α helix and the β-pleated sheet are part of which protein structure?

A. primary B. Secondary C. tertiary D. quaternary B. Secondary

A nucleotide of DNA may contain ________.

A. ribose, uracil, and a phosphate group B. deoxyribose, uracil, and a phosphate group C. deoxyribose, thymine, and a phosphate group D. ribose, thymine, and a phosphate group C. deoxyribose, thymine, and a phosphate group

Plant cell walls contain which of the following in abundance?

A. starch B. cellulose C. glycogen D. lactose B. cellulose

The building blocks of nucleic acids are ________.

A. sugars B. nitrogenous bases C. peptides D. nucleotides D. nucleotides

Phospholipids are important components of ________.

A. the plasma membrane of animal cells B. the ring structure of steroids C. the waxy covering on leaves D. the double bond in hydrocarbon chains A. the plasma membrane of animal cells

Saturated fats have all of the following characteristics except:

A. they are solid at room temperature B. they have single bonds within the carbon chain C. they are usually obtained from animal sources D. they tend to dissolve in water easily D. they tend to dissolve in water easily

Study Figure 3.23 Which categories of amino acid would you expect to find on the surface of a soluble protein, and which would you expect to find in the interior? What distribution of amino acids would you expect to find in a protein embedded in a lipid bilayer?

Polar and charged amino acid residues (the remainder after peptide bond formation) are more likely to be found on the surface of soluble proteins where they can interact with water, and nonpolar (e.g., amino acid side chains) are more likely to be found in the interior where they are sequestered from water. In membrane proteins, nonpolar and hydrophobic amino acid side chains associate with the hydrophobic tails of phospholipids, while polar and charged amino acid side chains interact with the polar head groups or with the aqueous solution. However, there are exceptions. Sometimes, positively and negatively charged amino acid side chains interact with one another in the interior of a protein, and polar or charged amino acid side chains that interact with a ligand can be found in the ligand binding pocket.