1. Unit 2 - Reproduction

2. 4.1 The Function of the Nucleus within the Cell
1. Animal Cells
Organelles = specialized cell parts
See page 122
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3. Animal Cell Parts and Organelles
cell membrane - thin covering that controls what enters & leaves the cell
cytoplasm - jelly-like substance that contains the organelles; where most of the chemical reactions occur
mitochondria - provide energy
ribosomes – makes proteins
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4. endoplasmic reticulum (er) - channels that act as a transport system for materials made in the cell; two types:
1. smooth – no ribosomes; makes fats & removes toxins
2. rough – has ribosomes; makes proteins
vesicles - sacs that transports substances
Golgi body - sorts & packages proteins for transport
nucleus - controls all cell activities

5. nucleolus - membrane-free organelle that makes ribosomes
nuclear membrane - protects the contents of the nucleus
nuclear pores - openings in the nuclear membrane that allow only certain materials to pass
vacuoles - membrane-bound storage containers

6. Plant Cell Parts and Organelles
2. Plant Cells
Contains many of the
same organelles as an
animal cell
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7. Unique plant cell organelles:
chloroplasts – contain chlorophyll to trap energy from Sun to make glucose (food for the plant)
cell wall - tough, rigid structure that surrounds cell membrane, provides protection & support
large vacuoles - for storing water & giving support

8. (c) McGraw Hill Ryerson 2007

9. (c) McGraw Hill Ryerson 2007
The Nucleus and DNA
The nucleus contains DNA (deoxyribonucleic acid)
DNA is the molecule has the master set of instructions for how cells function, what they will produce, & when they will die
See page 126
(c) McGraw Hill Ryerson 2007

10. DNA looks like a twisted ladder
The sides of the DNA ladder are made of sugar & phosphate.
The steps of the ladder are made of four nitrogen bases:
adenine (A)
guanine (G)
cytosine (C)
thymine (T)
The bases join in a specific way
A always joins with T
G always joins with C

11. DNA in the Nucleus Most of the time DNA is in the form of chromatin
Chromatin coils tightly into X-shaped chromosomes
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12. Every organism has a specific number of chromosomes
Human cells have 46 chromosomes arranged in 23 pairs
The 23rd pair determines sex:
XX for females
XY for males

14. (c) McGraw Hill Ryerson 2007
Genes
Genes = small segments of DNA
Genes store the information needed to make proteins
Each chromosome can carry thousands of genes
Every body cell has the same genes, but only some genes are “read” in each cell to produce specific proteins
Specialized proteins include enzymes & hormones
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(c) McGraw Hill Ryerson 2007

15. Proteins
Molecules that are needed for the structure, function, & regulation of the body's tissues and organs
Include enzymes and hormones
Examples:
lactase (enzyme) that speeds up the digestion of lactose
insulin (hormone) that regulates blood sugar levels

16. Production of Proteins
The nucleus receives a chemical signal to make a specific protein.
The DNA message for the protein is copied into a small molecule called RNA (ribonucleic acid).
RNA leaves the nucleus through a nuclear pore.
The RNA message is delivered to a ribosome
The ribosome makes the protein.

17. The protein enters the endoplasmic reticulum (ER).
A vesicle forms at the end of the ER, & carries the protein to the Golgi body.
The Golgi body modifies, sorts, & repackages the protein.
A vesicle forms off the end of the Golgi body to carry the protein to the cell membrane.
The vesicle attaches to the cell membrane, and its protein contents are released out of the cell.
See page 131

18. Take the Section 4.1 Quiz