Problem 15 - Biology: Concepts and Applications

Question

Match the terms appropriately. ______bacteriophage ______ clone ______nucleotide ______ diploid ______DNA ligase ______DNA polymerase ______ autosome a. nitrogen-containing base, sugar, phosphate group(s) b. copy of an organism c. does not determine sex d. only DNA and protein e. fills in gaps, seals breaks in a DNA strand f. two chromosomes of each type g. adds nucleotides to a growing DNA strand

Step-by-Step Solution

Answer

d, b, a, f, e, g, c

Step 1: Identify the Definition for Bacteriophage

Look at the options and identify which one corresponds to 'bacteriophage'. A bacteriophage is mostly composed of DNA and protein, matching with option d.

Step 2: Identify the Definition for Clone

Find the definition that matches a 'clone'. A clone is a copy of an organism, which corresponds to option b.

Step 3: Identify the Definition for Nucleotide

Determine what a 'nucleotide' would match. A nucleotide consists of a nitrogen-containing base, sugar, and phosphate group(s), matching with option a.

Step 4: Identify the Definition for Diploid

Match the term 'diploid' with its definition. A diploid is an organism with two chromosomes of each type, so it corresponds to option f.

Step 5: Identify the Definition for DNA Ligase

Look for the definition of 'DNA ligase'. DNA ligase fills in gaps and seals breaks in a DNA strand, which matches with option e.

Step 6: Identify the Definition for DNA Polymerase

Find the definition for 'DNA polymerase'. DNA polymerase adds nucleotides to a growing DNA strand, corresponding to option g.

Step 7: Identify the Definition for Autosome

Finally, match 'autosome' to its definition. An autosome does not determine sex, linking to option c.

Key Concepts

Bacteriophage

A bacteriophage, often referred to simply as a 'phage', is a type of virus that infects and replicates within bacteria. It is composed primarily of DNA (or RNA in some cases) and protein. These miniature entities have a complex structure that allows them to bind specifically to bacterial cells, injecting their genetic material inside.
Once inside the bacterium, the phage's DNA takes over the bacterial machinery to reproduce more viruses. Bacteriophages play a crucial role in bacterial ecology and can be used for purposes such as phage therapy, a promising approach to combat antibiotic-resistant bacterial infections. They are a major tool in the study of molecular biology and genetics.

Clone

In biology, a clone refers to an organism or cell that is an exact genetic replica of another. This can occur naturally, as in the case of identical twins, or be created artificially in a laboratory setting. Cloning can involve duplicating entire organisms or just specific cells or genetic material.
There are several types of cloning, including:

• Reproductive Cloning: Producing a copy of an entire organism.
• Therapeutic Cloning: Creating embryonic stem cells for medical use.
• Gene Cloning: Making copies of specific genes.

Clones are valuable in research because they provide consistent models for studying diseases and developing treatments.

Nucleotide

Nucleotides are the basic building blocks of nucleic acids, such as DNA and RNA. Each nucleotide consists of three components:

• A nitrogen-containing base (adenine, guanine, cytosine, thymine for DNA, and uracil replacing thymine in RNA).
• A five-carbon sugar (deoxyribose in DNA and ribose in RNA).
• One or more phosphate groups.

Nucleotides play essential roles not just in building DNA and RNA, but also in cell signaling, metabolism, and enzyme reactions as molecules like ATP.

Diploid

The term diploid refers to cells that contain two complete sets of chromosomes, one from each parent. In humans and many other organisms, diploid cells are the standard; they carry pairs of homologous chromosomes, meaning each chromosome has a partner that is its exact duplicate in terms of structure and gene sequence.
These cells are marked by a ploidy number of 2n, which, for humans, equals 46 chromosomes. Diploid cells are important because they ensure genetic diversity through sexual reproduction, where each parent contributes one set of chromosomes to the offspring.

DNA Ligase

DNA ligase is a critical enzyme in DNA metabolism. It functions by sealing nicks and joining broken strands of DNA during replication, recombination, and repair.
The enzyme works by catalyzing the formation of a phosphodiester bond between the phosphate backbone of DNA, effectively linking strands or fragments. This action is crucial in processes like:

• DNA Replication: Joining Okazaki fragments on the lagging strand.
• DNA Repair: Fixing single-strand breaks.
• Recombinant DNA Technology: Essential for cloning and genetic engineering.

Without DNA ligase, cells would not be able to replicate their DNA or repair damage efficiently.

DNA Polymerase

DNA polymerase is an enzyme that plays a fundamental role in DNA replication. It is responsible for synthesizing new DNA strands by adding complementary nucleotides to an existing strand or template.
The enzyme reads the existing strands to guide the incorporation of new nucleotides, ensuring the base pairing rules (A with T, and G with C) are followed. Multiple types of DNA polymerases exist, each specialized in particular tasks, such as:

• Replication: As in leading and lagging strand synthesis.
• Proofreading: Ensuring accuracy by correcting errors.
• Repair: Fixing DNA damages through various repair mechanisms.

This precision is critical for maintaining genetic fidelity and stability.

Autosome

Autosomes are the chromosomes that do not determine the sex of an organism but carry the bulk of the genetic information that makes up an organism's traits. In humans, there are 22 pairs of autosomes, with the 23rd pair being the sex chromosomes (X and Y).
Autosomes are called such because their genes are inherited equally from both parents, and they carry genes that code for a wide variety of functions and characteristics in an organism. These chromosomes ensure that essential genetic information is passed down, contributing to traits like eye color, height, and susceptibility to certain diseases.