34 WJEC Biology AS Level - Marianne Izen - 2nd Edition Flashcards
What does SI stand for?
SI stands for Système Internationale, the system that defines which units are used for scientific communication.
What is the most prominent feature in the cell?
The nucleus is the most prominent feature in the cell.
What is the shape and size of the nucleus?
It is usually spherical and 10-20 μm in diameter.
What does the nucleus contain?
It contains DNA which, with protein, comprises the chromosomes.
What is the function of the chromosomes?
The chromosomes direct protein synthesis because they are the site of transcription.
What does the DNA provide a template for?
The DNA also provides a template for DNA replication.
What is the nucleus bounded by?
It is bounded by two membranes, called the nuclear envelope, with pores.
What is the function of the nuclear pores?
It allows the passage of large molecules, such as mRNA, and ribosomes out of the nucleus.
What is the outer nuclear membrane continuous with?
The outer membrane is continuous with the endoplasmic reticulum.
What is the nucleoplasm?
The granular material in the nucleus is nucleoplasm.
What does the nucleoplasm contain?
It contains chromatin, which is made of coils of DNA bound to protein.
What happens to chromatin during cell division?
During cell division, chromatin condenses into chromosomes.
What is the nucleolus?
Within the nucleus are one or more small spherical bodies, each called a nucleolus.
What is the function of the nucleolus?
They are the sites of formation of rRNA, a constituent of ribosomes.
Is it correct to say the nucleus produces proteins?
It is not correct to say that the nucleus produces proteins. However, it is correct to say that DNA codes for their production.
Draw a table of the SI units of length with the following columns:
Measurement | Symbol | Number per metre | Number of metres | Object measured
Draw a diagram of the electron micrograph of the nucleus and label its parts.
