The NucleusDo Now: (Challenge Extra Credit!)

The cells of plant seeds store oils in the form of droplets enclosed by membranes. These membranes are very different from the cell membrane even though they are made of the same phospholipids.

Draw a simple model for a membrane around an oil droplet, and briefly explain why this arrangement is more stable than bilayer.

hydrophobic

hydrophilic

Since the oil is hydrophobic, this membrane has only ONE LAYER. Polar head groups on the outside, hydrophobic tails in the oil

The nucleus is a small sphere that holds all of a cell’s DNA.

The Nucleus

Structure & Function

• Structure: spherical lipid membrane (like cell membrane) that contains DNA.

• Function: Stores DNA, controls cell activity

It is found ONLY in EUKARYOTIC cells.

Dolly the SheepDolly was the first clone of an adult mammal ever made.

Dolly was born in 1997, she died a few years later, younger than usual for a sheep.

So what does a cloned sheep have to do with a cell nucleus?

When adult animals are cloned, it is by adding a nucleus

from a cell to a new egg cell without a nucleus.

How to Make a Sheep.

nuclear envelope: A lipid bilayer that surrounds the

nucleus

nuclear pores: openings in the

nuclear envelope

Most of the inside of a nucleus is made up of chromatin, which is a mix of DNA

and related proteins.

The nucleolus is a small dark part inside a nucleus where ribosomes are

made.

Find those parts:

Nuclear Envelope

Nuclear Pores

Chromatin

Nucleolus

SUPER IMPORTANT CELL PARTS: NUCLEUS

• STRUCTURE: Sphere in the center of a cell that contains all of the DNA

• FUNCTION: Controls cell functions & stores genetic information

Homework… read all about it!

• “Nucleus” p. 81 , SR #3 p. 83