chapter 10 biochemistry of the Genome

What is the genetic material responsible for heredity?

DNA, which transmits traits from one generation to the next.

What significant discovery was made in the late 1800s?

The discovery of nucleic acids.

How does DNA function in relation to proteins?

DNA carries instructions for making all proteins in an organism, akin to a recipe.

What is the process by which external DNA is taken up by a cell?

Bacterial transformation.

Who conducted the transformation experiments that demonstrated hereditary information transfer?

Bacteriologist Frederick Griffith.

What are the two strains of Streptococcus pneumoniae used in Griffith's experiments?

R strain (nonpathogenic, rough appearance) and S strain (pathogenic, smooth appearance).

What was the outcome when live R strain was injected into mice?

The mice survived.

What happened when live S strain was injected into mice?

The mice died.

What was the result of injecting a mixture of rough strain and heat-killed smooth strain into mice?

The mice died, and bacteria recovered were pathogenic S strain.

What conclusion did Griffith draw from his experiments?

Something had passed from the heat-killed S strain into the live R strain, transforming it into pathogenic S.

What is the difference between genotype and phenotype?

Genotype refers to the genes an organism has, while phenotype refers to the traits expressed by those genes.

What did Avery's experiments aim to determine?

The identity of the hereditary material responsible for transformation.

What was the result when DNA was degraded in Avery's experiments?

Transformation did not occur; thus, DNA was identified as the genetic material.

What is horizontal gene transfer?

The transfer of genetic material within the same generation, such as between bacterial siblings.

What is the structure of DNA?

DNA is a polymer made up of nucleotide monomers.

What are the basic building blocks of DNA?

Nucleotides.

What are the four nitrogenous bases found in DNA?

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

Which nitrogenous base is only found in DNA?

Thymine (T).

What type of bond exists between Cytosine and Guanine?

Cytosine (C) is always bound to Guanine (G).

What is the significance of the experiments conducted by Oswald Avery and colleagues?

They confirmed that DNA is the transforming principle in Griffith's transformation experiments.

What role does heat play in Griffith's transformation experiments?

Heat is used to kill the S strain of S. pneumoniae, allowing the study of its components.

What happens to the R strain when DNA is present in the transformation experiments?

The R strain is transformed into the pathogenic S strain.

What is the relationship between DNA and proteins in the context of genetic information?

DNA stores and transfers genetic information needed for protein synthesis.

Which nitrogenous bases are found in DNA?

Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).

How do adenine and thymine pair in DNA?

Adenine (A) pairs with Thymine (T) through two hydrogen bonds.

What is the role of covalent bonds in DNA?

Covalent bonds, known as phosphodiester bonds, link individual nucleotides together, forming the sugar-phosphate backbone.

What is the significance of the 5' and 3' ends of DNA strands?

The 5' end has a free phosphate group, and the 3' end has a free hydroxyl group, indicating the directionality of the DNA strand.

What is the function of DNA?

DNA contains the instructions for making all proteins in an organism and is transmitted from parent to daughter cells.

What is RNA and how does it differ from DNA?

RNA (Ribonucleic acid) is usually single-stranded, contains ribose sugar, and has uracil (U) instead of thymine (T).

What are the three types of RNA and their functions?

1. Messenger RNA (mRNA) carries instructions from DNA to ribosomes. 2. Transfer RNA (tRNA) brings amino acids to ribosomes. 3. Ribosomal RNA (rRNA) is part of the ribosome and helps align mRNA and tRNA.

What is the process of transcription?

Transcription is the process where DNA is copied into mRNA.

What is the process of translation?

Translation is the process where mRNA is used to synthesize proteins at the ribosome.

What is a gene?

A gene is a region of DNA that specifies the amino acid sequence of a protein.

What are constitutive genes?

Constitutive genes are those that are always expressed, regardless of environmental conditions.

Where are chromosomes located in eukaryotic and prokaryotic cells?

In eukaryotic cells, chromosomes are found in the nucleus; in prokaryotic cells, they are located in the cytoplasm.

What are plasmids?

Plasmids are smaller loops of DNA found in bacteria that may contain genes not essential for normal growth and can be exchanged between bacteria.

What is the role of hydrogen bonds in DNA?

Hydrogen bonds stabilize the complementary base pairs (A=T and G≡C) in the DNA double helix.

What is the sugar-phosphate backbone?

The sugar-phosphate backbone is formed by covalent bonds between the phosphate group of one nucleotide and the sugar of the next nucleotide.

What is the significance of base pairing in DNA?

Base pairing ensures that the genetic information is accurately copied and transmitted during DNA replication.

What is the function of mRNA in protein synthesis?

mRNA serves as an intermediary that carries genetic information from DNA to the ribosome for protein synthesis.

How does tRNA contribute to protein synthesis?

tRNA transfers the correct amino acid to the ribosome, matching it with the corresponding codon on the mRNA.

What is the role of rRNA in the ribosome?

rRNA helps ensure the proper alignment of mRNA and tRNA during protein synthesis and catalyzes peptide bond formation.