Chromosomes, Genes & Proteins

 

What Are Chromosomes, Genes, and Proteins?

• Chromosomes:

  • Thread like structures made of DNA (deoxyribonucleic acid), which stores genetic information in genes.
  • Found in the nucleus of cells.
  • Human cells typically contain 46 chromosomes (23 pairs).

• Genes:

  • A gene is a specific length of DNA that codes for a protein.
  • Think of genes as "recipes" for making proteins, which carry out specific tasks in the body.

• Alleles:

  • Different versions of the same gene are called alleles.
  • Alleles give organisms their different and unique characteristics.
  • Example: Eye color is determined by different alleles of the eye color gene.

 

How DNA and Proteins Are Related

• DNA Structure:

  • DNA is like a spiral ladder made of base pairs (Adenine [A], Thymine [T], Cytosine [C], Guanine [G]).
  • The sequence of these bases forms the "instructions" for making proteins.

• Proteins:

  • Proteins are made of amino acids, which are assembled in specific sequences based on DNA instructions.
  • Proteins determine traits like height, eye color, and hair texture.

Key Concept	Details
Haploid Nucleus	Contains one set of chromosomes (e.g., sperm or egg cells).
Diploid Nucleus	Contains two sets of chromosomes (e.g., most body cells).
Human Chromosomes	23 pairs in diploid cells, with one pair determining sex (XX or XY).

 

How Genes Make Proteins

1. Gene Coding for a Protein Remains in the Nucleus:

   • The gene holds the instructions for making a specific protein.

2. Messenger RNA (mRNA):

   • A copy of the gene is made as mRNA.
   • mRNA moves out of the nucleus to the cytoplasm.

3. Ribosomes Assemble Proteins:

   • Ribosomes "read" the mRNA and assemble amino acids into a protein.

4. Sequence Determines Shape and Function:

   • The sequence of amino acids determines the protein's shape and job.