Nucleus Flashcards
What’s the importance of proteins
-Enzymes for chemical reactions
-Structural proteins e.g. organelle movement
-Transport molecules e.g. haemoglobin. (Transports oxygen).
Describe transcription
-The instructions for encoding the amino acid sequence of a protein are contained within the gene for that protein.
-To synthesise a protein, the generic information encoded by that gene is converted to mRNA
Describe translation
A ribosome reads the info contained in the mRNA and synthesises the protein molecule
What happens if the protein remains in the cytoplasm
If the protein remains in the cytoplasm, e.g. a cellular enzyme, then translation will take place on a free ribosome in the cytoplasm.
What happens if the proteins are secreted from cells
Secreted proteins are translated on a ribosome attached to the rough endoplasmic reticulum. These proteins then make their way through the rough ER and the Golgi apparatus before leaving the cell.
What material does the nucleus contain
Nucleoplasm- contains molecules such as nucleotides and enzymes, which are needed for DNA and RNA synthesis.
What surrounds the nucleus
A double membrane- nuclear envelope.
What’s within the nuclear envelope
Nuclear pores- allows molecules to enter and leave nucleus.
What’s the outer membrane of the nuclear envelope continuous with
Rough endoplasmic reticulum
What is chromatin
Chromatin consists of DNA coiled around proteins called histones, together, the DNA and histone proteins form chromosomes.
Are chromosomes visible in the nucleus
No, unless they are undergoing mitosis or meiosis.
What’s the nucleolus
The nucleolus is where a special type of RNA is produced- ribosomal RNA or rRNA.
