Question

Genes a. are the basic units of inheritance. b. are located on chromosomes and composed of DNA. c. commonly contain instructions for building a single protein. d. all of the above

Short answer

d. all of the above

Step-by-step solution

- Analyze Each Option

Read each option carefully to understand what it is stating. A clear understanding of the definitions and components of genes will help in the analysis.

- Verify Option a

Option a states that genes are the basic units of inheritance. This is correct because genes carry hereditary information from parents to offspring.

- Verify Option b

Option b states that genes are located on chromosomes and composed of DNA. This is also correct. Genes are segments of DNA located on chromosomes.

- Verify Option c

Option c states that genes commonly contain instructions for building a single protein. This is accurate as genes encode for proteins through the processes of transcription and translation.

- Conclude with Option d

Since options a, b, and c are all correct, option d, which states 'all of the above,' must be the correct choice.

Key concepts

Inheritance

Inheritance refers to the process by which genetic information is passed from parents to their offspring. This genetic information resides in genes, which are segments of DNA on chromosomes. Inheritance patterns can be complex, but fundamentally:

• Genes carry the codes that determine specific traits.
• Traits can be dominant or recessive, depending on the alleles inherited.
• Genetic inheritance follows Mendelian principles, including the segregation of alleles and independent assortment.

Understanding inheritance helps us to predict how traits are passed down and how genetic disorders might occur in a family lineage.

Chromosomes

Chromosomes are structures within cells that contain DNA and proteins. Humans have 23 pairs of chromosomes in each cell. Key points to remember about chromosomes:

• Each chromosome consists of a long DNA molecule coiled around proteins called histones.
• Chromosomes ensure DNA is accurately replicated and divided during cell division.
• They are visible under a microscope during cell division, appearing as X-shaped structures.

Chromosomes play a crucial role in genetics, as genes are situated on them, and they carry the hereditary material from parents to offspring.

DNA

DNA, or deoxyribonucleic acid, is the molecule that holds the instructions an organism needs to develop, live, and reproduce. Key features of DNA include:

• It is composed of two strands that form a double helix.
• Each strand consists of a sugar-phosphate backbone and nitrogenous bases (adenine, thymine, cytosine, and guanine).
• The order of these bases encodes genetic information.

DNA sequences are transcribed into RNA, which is then translated into proteins that carry out various functions in the cell.

Proteins

Proteins are molecules that serve many functions in the body, from building cellular structures to catalyzing chemical reactions. Important facts about proteins include:

• They are composed of long chains of amino acids.
• The sequence of amino acids in a protein is determined by the genetic code in a gene.
• Proteins can be enzymes, hormones, structural components, and more.

The gene-to-protein process involves transcription of DNA into RNA and translation of RNA into a protein, a process known as gene expression.