PCB 3063 - Lecture 1 DNA Structure

What is genetics?

The study of heredity and variation.

Define heredity.

The passing down of traits from one generation to another.

What does variation refer to in genetics?

Differences in inherited characteristics among members of a population.

What is transmission genetics?

The study of how traits are passed down between generations.

What is molecular genetics?

The study of the structure and function of individual genes, including cancer genetics and genetic engineering.

What is population/evolutionary genetics?

The study of genetic variation in populations, including conservation genetics.

What is the difference between a nucleus and a nucleoid?

The nucleus is a membrane-enclosed organelle in eukaryotic cells, while the nucleoid is a region in prokaryotic cells where the chromosome resides.

What is a chromosome?

A single piece of DNA associated with proteins, which can be linear in eukaryotes or circular in prokaryotes.

What defines a gene?

A defined segment of a chromosome that provides instructions to make a single product (a protein).

What is the difference between diploid and haploid cells?

Diploid cells have two copies of each chromosome (2n), while haploid cells have one copy (1n).

What are alleles?

Alternate forms of the same gene caused by minor differences in the DNA sequence.

Differentiate between genotype and phenotype.

Genotype is the genetic makeup of an organism, while phenotype is the observable characteristics influenced by genotype and environment.

What are transcription and translation in genetics?

Transcription is the process of copying DNA instructions into RNA, while translation is the process of reading RNA to make a protein.

What was the early view of genetics before the 1800s?

Early genetics was more philosophical than scientific, with many incorrect concepts like pangenesis and blending inheritance.

How did technological advancements in the 1800s impact genetics?

Inventions like microscopes allowed for direct observation of gametes, leading to the revolutionization of genetics by figures like Darwin and Mendel.

What was the significance of Griffith's transformation study?

It provided evidence that DNA is the genetic material by showing that live R strain bacteria could transform into live S strain when mixed with dead S strain.

What was the misconception about the genetic material before DNA was accepted?

Many believed that proteins, due to their complexity and abundance, were the genetic material instead of DNA.

What is the role of chromosomes in genetics?

Chromosomes carry genetic information, consisting of DNA and proteins.

What is the relationship between chromosomes and genes?

Chromosomes are divided into genes, which are composed of DNA.

What is the importance of the study of cancer genetics?

It focuses on understanding the genetic basis of cancer, which is crucial for developing targeted therapies.

What is conservation genetics?

A subfield of population genetics that focuses on the genetic diversity of species and their conservation.

What is the significance of the 1910 Levene study?

It suggested that DNA was repetitive, which was later disproven as more complex structures were discovered.

What did Avery, MacLeod, and McCarty demonstrate in 1944?

They demonstrated that DNA was the transforming principle.

What was the main finding of the Hershey and Chase experiment in 1952?

Radioactive phosphorus was injected, indicating that DNA is the genetic material.

What is the significance of diploid cells in relation to haploid cells?

Diploid cells contain twice the amount of genetic material than haploid cells.

At what wavelength does UV light mutate genetic material?

UV light at a wavelength of 260 nm mutates genetic material.

What are the four nitrogenous bases found in DNA?

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

What distinguishes purines from pyrimidines in DNA?

Purines (A and G) have two rings, while pyrimidines (T and C) have one ring.

How are nucleotides in DNA connected?

Nucleotides are connected via phosphodiester bonds between the 5' phosphate group of one nucleotide and the 3' OH group of another.

What is the structure of DNA as proposed by Watson and Crick?

DNA is a double-stranded polynucleotide that adopts a right-handed helix.

What is Chargaff's rule regarding base pairing in DNA?

The amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

What are the major and minor grooves in DNA?

They are empty spaces in the 3-D structure of the double helix, common locations for protein binding.

What is B-DNA?

The type of DNA described by Watson and Crick, found in most normal cells.

What is A-DNA and when is it observed?

A-DNA is observed when water is removed from DNA; it is more compact than B-DNA.

What characterizes Z-DNA?

Z-DNA has a zig-zag shape, is a left-handed helix, and is formed mostly with C-G base pairs.

How do some bacteria utilize A-DNA?

Some bacteria form protective endospores by converting B-DNA to A-DNA to protect against harsh conditions.

What is the primary structural difference between RNA and DNA?

RNA is mostly single-stranded and contains ribose sugar, while DNA is double-stranded and contains deoxyribose.

What base does RNA contain instead of thymine?

RNA contains uracil (U) instead of thymine (T).

What role does RNA play in certain viruses?

RNA serves as the genetic material for a number of viruses, including influenza and HIV.

What is the composition of a nucleotide in DNA?

Each nucleotide contains a 5-carbon sugar (deoxyribose), a phosphate group, and one of four nitrogenous bases.

What is the significance of the 5' and 3' ends of a polynucleotide?

The 5' end has a free phosphate group, while the 3' end has an unbound hydroxyl group.

What is the role of hydrogen bonds in DNA structure?

Hydrogen bonds form between A-T (2 bonds) and C-G (3 bonds) pairs, stabilizing the double helix.

What evidence supports that DNA is the universal genetic material?

Direct evidence from genetic engineering shows that adding DNA to a cell results in expected protein production.

What is the relationship between protein concentrations in diploid and haploid cells?

Protein concentrations are the same in both diploid and haploid cells, despite differences in genetic material.

What happens to DNA when it is exposed to UV light?

DNA absorbs UV light at 260 nm, which can lead to mutations.

What is the significance of the alternating major and minor grooves in DNA?

They are common locations for protein binding, influencing gene expression and regulation.

What is the function of SASPs in bacteria?

SASPs bind to DNA and convert it from B-DNA to A-DNA, protecting it from damaging agents.