Cytology Chapter 2: Molecular Components of the Cell

A comprehensive set of 60 flashcards covering the molecular components of the cell, including amino acids, proteins, lipids, carbohydrates, and nucleic acids, based on the cytology lecture transcript.

What type of bond links amino acids together in a polypeptide chain?

Peptide bonds

What determines the electric charge of an amino acid?

The charge is pH-dependent

Which type of bond is formed between two cysteine residues in a protein?

A disulfide bond

What is the composition of a ceramide?

A sphingosine and a fatty acid

How many fatty acids and glycerol molecules are found in a single triglyceride?

Three fatty acids and one glycerol molecule

What type of chemical bonds link fatty acids to glycerol in a triglyceride?

Ester bonds

True or False: Phospholipids are amphipathic components of biological membranes.

True

Which glycolipid contains a simple sugar and is abundant in the nervous system?

Cerebroside

What is the general chemical formula for simple oses (monosaccharides)?

$$C_nH_{2n}O_n$$

Which homopolysaccharide is known for being a branched storage form of glucose?

Glycogen

What type of bond links monomers together in disaccharides and polysaccharides?

Glycosidic bond

Which substance is a heteropolysaccharide typically found in the extracellular matrix?

Chondroitin sulfate

In a nucleotide, what type of bond links the nitrogenous base to the pentose sugar?

An N-glycosidic bond

What is the diameter of the B-DNA helix?

$2\,\text{nm}$ (or $20\,\text{\AA}$)

What is the length (pitch) of one full turn of the B-DNA helix?

$$3.4\,\text{nm}$$

What type of secondary structure is characteristic of transfer RNA (tRNA)?

A trefoil (cloverleaf) structure

What is the characteristic tertiary structure shape of a tRNA molecule?

An inverted L-shape

Which carbon atoms of the pentose sugars are linked by a phosphodiester bond in nucleic acids?

The $5'$ carbon of one nucleotide and the $3'$ carbon of the previous one

Which protein structure level is defined by the specific sequence of amino acids?

Primary structure

What type of bonds are primarily responsible for stabilizing the secondary structure of proteins, such as the alpha helix?

Hydrogen bonds

What is the term for the loss of a protein's 3D structure due to factors like heat?

Denaturation

What are the two major types of secondary structures found in proteins?

Alpha helix and beta pleated sheet

In which direction is an amino acid chain synthesized?

From the N-extremity to the C-extremity

Which atoms repeat to form the backbone of a protein?

$$-N-C-C-$$

At what minimum number of carbon atoms does a monosaccharide typically adopt a cyclic configuration?

Five

What is the difference between a nucleotide and a nucleoside?

A nucleoside does not contain a phosphate group

Which nitrogenous bases are found in ribonucleotides?

Adenine (A), Uracil (U), Cytosine (C), and Guanine (G)

What is a holoprotein?

A protein conjugated to non-amino acid molecules

Which homopolysaccharide found in arthropod exoskeletons is a polymer of N-acetyl glucosamine?

Chitin

True or False: Saturated and unsaturated fatty acids are totally nonpolar molecules.

False (they have a polar carboxyl group)

Which part of a fatty acid reacts with glycerol to form a lipid?

The carboxyl group

What are the components of a nucleotide?

A nitrogenous base, a pentose sugar, and a phosphate group

How are the two strands of a DNA molecule held together?

By hydrogen bonds between complementary bases

Which class of RNA is considered the most diverse in terms of sequence?

Messenger RNA (mRNA)

What molecule is released when two monomers are linked by a glycosidic or peptide bond?

Water (H2O)

Which specific lipids are precursors of steroid hormones?

Sterols (like cholesterol)

What defines a tertiary structure in proteins?

The 3D folding of the polypeptide chain into a globular or fibrous shape

What type of bonds maintain the primary structure of a protein?

Covalent peptide bonds

What role do disulfide bridges play in protein structure?

They stabilize the tertiary (and sometimes quaternary) structure

Which nitrogenous base is unique to DNA and not found in RNA?

Thymine (T)

Which nitrogenous base is unique to RNA and not found in DNA?

Uracil (U)

How do water molecules bind to one another?

Via hydrogen bonds enabled by their polarity

Which modified monosaccharide polymerizes to form chitin?

N-acetyl glucosamine

What is phosphatidylcholine?

A glycerophospholipid comprising a diglyceride, a phosphate, and a choline

Which polysaccharide is an unbranched (linear) homopolysaccharide?

Cellulose

In a nucleic acid sequence with 8 A, 7 T, 6 C, and 7 G, how many purine bases are present?

15 (A + G = 8 + 7)

How many base pairs are typically found in one turn of the B-DNA helix?

10 base pairs

What is the sequence of the $3'$ end of all tRNA molecules?

CCA

What term describes molecules that have both hydrophobic and hydrophilic regions, such as phospholipids?

Amphiphilic (or amphipathic)

True or False: Mineral salts can act as cofactors for certain proteins.

True

Which ion plays a crucial role in actin-myosin interaction and functions as a second messenger?

Calcium ($Ca^{2+}$)

Besides DNA and proteins, what is the third major class of macromolecules in living things?

Polysaccharides

What happens to the function of a protein when its 3D structure is altered?

The function is usually lost or compromised

Are triglycerides saponifiable or non-saponifiable?

Saponifiable

Wait is the sugar found in DNA?

Deoxyribose

What is the sugar found in RNA?

Ribose

Which level of protein organization involves the arrangement of multiple protein subunits?

Quaternary structure

Where does the transcription of genes into RNA occur in eukaryotes?

In the nucleus

True or False: Water abundance in cells is constant across all cell types.

False (it varies among cell types)

What is the relationship between a protein's primary structure and its tertiary structure?

The primary structure determines the tertiary structure