Threads, rods and genes
How the instructions for inheritance are packed.
Instructions for a body
Every cell has a long set of instructions, passed on from parents to the next generation.
Where in the cell are these instructions kept?
What this lesson covers
The idea
Chromosomes, made of DNA and proteins, carry information for inheritance; DNA holds the genetic information and its functional segments are genes; in a non-dividing cell DNA lies in thread-like chromatin, which organises into chromosomes before division.
Instructions for a body
Every cell has a long set of instructions, passed on from parents to the next generation.
Where in the cell are these instructions kept?
- In the nucleus, on the chromosomes
- In the cell wall
- In the vacuole
Zoom into the nucleus
Press + to zoom in, step by step.
Chromatin, chromosomes, DNA, genes
Chromosomes, made of DNA and proteins, carry the information for inheritance. DNA holds the genetic information; its functional segments are genes. In a non-dividing cell, DNA is in thread-like chromatin, which organises into chromosomes before the cell divides.
Chromosomes pass information for inheritance from parents to the next generation.
- Name | What it is
- Chromatin | entangled thread-like mass in a non-dividing cell
- Chromosome | rod-shaped, seen when the cell is about to divide
- DNA | molecule that carries genetic information
- Gene | a functional segment of DNA
Notes
Chromosomes (DNA + proteins) carry the information for inheritance. DNA holds it, and genes are its functional segments. In a non-dividing cell DNA is chromatin.
Check yourself
A chromosome is made of…
A gene is…
In a non-dividing cell, DNA is present as…
When does the chromatin become rod-shaped chromosomes?
- DNA and proteins — correct. Yes.
- only water. Chromosomes are made of DNA and proteins.
- only fat. Chromosomes are made of DNA and proteins.
- a functional segment of DNA — correct. Yes.
- a whole cell. A gene is a segment of DNA.
- a kind of membrane. A gene is a segment of DNA.
- chromatin, a mass of thread-like structures — correct. Yes.
- rod-shaped chromosomes. Those appear when the cell is about to divide.
- a cell wall. The wall is not DNA.
- When the cell is about to divide — correct. Yes.
- Never. It does, before division.
- Only after the cell dies. It happens before division.