Genomes and DNA/RNA

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary component of most genomes, including the human genome?

Carbohydrates

RNA (ribonucleic acid)

DNA (deoxyribonucleic acid) (correct)

Proteins

What is the structure of DNA molecules described in the text?

A circular molecule

A triple helix

A single linear strand

Two polynucleotides wound around one another in a double helix (correct)

How many genes are present in the human nuclear genome according to the text?

16,569

3,235,000,000

45,500 (correct)

What is the length of the longest chromosome in the human nuclear genome?

250,000,000 base pairs Signup and view all the answers

How many genes are present in the human mitochondrial genome according to the text?

37 Signup and view all the answers

What is the shape of the human mitochondrial genome described in the text?

Circular Signup and view all the answers

What is the role of the transforming principle in the experiment involving mice and Streptococcus pneumoniae?

Converting harmless bacteria into a virulent form Signup and view all the answers

Which enzyme has an effect on the transforming principle in the lower two panels of the experiment?

Helicase Signup and view all the answers

What was labeled with 32P in the Hershey–Chase experiment involving T2 bacteriophages?

DNA of the bacteriophages Signup and view all the answers

What happens to the culture in the Hershey–Chase experiment after agitation to detach empty phage particles?

Culture is centrifuged to collect bacteria plus phage genes Signup and view all the answers

What is the function of T2 bacteriophages in the Hershey–Chase experiment?

Injecting genes into bacterial cells Signup and view all the answers

Which organism serves as a source of the transforming principle in the experiment involving mice?

Streptococcus pneumoniae Signup and view all the answers

What was the main finding of Hershey and Chase's experiment with 32P and 35S labels?

The bacterial pellet contained most of the phage DNA but little of the phage protein. Signup and view all the answers

What was found in the new phages produced at the end of the infection cycle?

They contained less than 1% of the protein from the parent phages. Signup and view all the answers

What is the approximate number of base pairs in the human nuclear genome?

3,235,000,000 base pairs Signup and view all the answers

How many chromosomes do diploid human somatic cells typically have?

46 chromosomes Signup and view all the answers

What is the approximate number of copies of the mitochondrial genome present in human somatic cells?

2000-7000 copies Signup and view all the answers

What is the primary difference between somatic cells and gametes (sex cells) in terms of their chromosome content?

Somatic cells are diploid, while gametes are haploid. Signup and view all the answers

Study Notes

Genomic Composition and Structure

Most genomes, including the human genome, are primarily composed of DNA.
DNA molecules are structured as double helices, consisting of two long strands that coil around each other, forming a spiral shape.

Gene Count and Chromosome Information

The human nuclear genome contains approximately 20,000 to 25,000 genes.
The longest chromosome in the human nuclear genome is chromosome 1, measuring about 248 million base pairs in length.
The human mitochondrial genome encompasses a much smaller number of genes, around 37.
The shape of the human mitochondrial genome is circular.

Transforming Principle and Experiments

The transforming principle in the studies involving mice and Streptococcus pneumoniae refers to the substance that could cause non-virulent bacteria to become virulent.
In the experiment, the enzyme that affects the transforming principle is deoxyribonuclease (DNase), which degrades DNA.

Hershey–Chase Experiment

In the Hershey–Chase experiment, phosphorus-32 (32P) was used to label the DNA of T2 bacteriophages.
After agitation to detach empty phage particles, only radioactive material (marked by 32P) remains in the bacterial cells.
T2 bacteriophages function as viral agents to inject their genetic material into bacteria, specifically Escherichia coli, during the experiment.

Key Findings and Outcomes

Hershey and Chase found that, following the experiment, only the 32P-labeled DNA entered the bacterial cells, indicating DNA carries genetic information, not proteins (which were labeled with sulfur-35 (35S)).
New phages produced at the end of the infection cycle contained radioactive labels corresponding to the DNA of the original phages.

Genetic Information in Humans

The human nuclear genome consists of approximately 3 billion base pairs.
Diploid human somatic cells typically have 46 chromosomes, arranged in 23 pairs.
Human somatic cells contain approximately 1,000 to 2,000 copies of the mitochondrial genome.
Somatic cells are diploid (containing two sets of chromosomes), while gametes (sex cells) are haploid (containing one set of chromosomes).

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fundamental concepts of genomes and DNA/RNA in living organisms. Learn about the construction and maintenance of organisms through genetic information contained in their genomes.