Download Section 4.1.notebook

Section 4.1.notebook
December 03, 2010
Unit 2 - Reproduction
Reproduction
Role of Nucleus
Asexual
Reproduction
Sexual
Reproduction
Nov 28­3:17 PM
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Section 4.1.notebook
December 03, 2010
Chapter 4 - The Nucleus Controls the Functions of Life
Objectives:
• Describe the role of the nucleus in controlling cell function,
growth, and division
• Distinguish between genes and chromosomes
• Describe factors that may lead to changes in a cell's
genetic information
• Demonstrate an understanding of how mutations occur
Section 4.1: The Function of the Nucleus within the Cell
“Traits” are characteristics (or properties, or features)
organisms have inherited from their parent(s)...like eye color,
body chemistry, nose shape, etc.
“Heredity” is the process of passing trait information onto the
next generation. This involves copying your genetic material and
placing it into new cells.
“Genetics” is the study of heredity.
Nov 28­3:39 PM
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December 03, 2010
Main Parts of a Cell
• Nucleus
• Cell membrane/wall
• Cytoplasm
• Mitochondria
These are called organelles.
There are two groups of cells (you are not responsible to know this)
Prokaryotic cells - their genetic material is often a ring ( a “plasmid”) of a molecule
called RNA found somewhere in the cell cytoplasm. Considered older, simpler, and more
ancient cell species than...
Eukaryotic cells - have DNA molecules inside their nucleus ( “chromatin” spread out
tangled DNA.... “chromosomes”...coiled, tightened X- shaped bundles of DNA)
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In eukaryotic cells, it is the nucleus that controls the day
to day activities of the cell:
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•
•
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•
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obtain nutrients
change these nutrients into energy
grow
repair themselves
reproduce
get rid of waste
The nucleus contains the master set of instructions that decides
how a cell works, when it will grow, when to reproduce, and when to
die. The instructions in the nucleus are carried in long, twostranded molecules called DNA ( deoxyribonucleic acid ). The DNA
molecule is a double helix (looks like a twisted ladder). It is the
molecule where your genetic information. DNA‛s instructions guide
the cell‛s day to day workings, and controls the cell‛s reproduction.
Chromosome
Chromosome
Spread­out tangled DNA called chromatin
DNA ­ double helix
­ twisted ladder
DNA ­ double helix
­ twisted ladder
Centromere
Centromere
unreplicated
chromosome
chromosome
Can only see chromosomes when a cell is ready to divide or reproduce.
Nov 28­4:28 PM
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Extra Information - you are not responsible for this
(DNA structure)....the “double helix”....shaped like a twisted
ladder
- phosphate and sugars make up the two sides
- pairs of shape matching “nitrogen base” make up
the middle steps
C matches with G
A matches with T
The order ( sequence ) of A‛s, C‛s, T‛s, and G‛s are
recipes that tell the cell how to make protein molecules.
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Most of the time, DNA exists in the nucleus in a loosely coiled
form. When a cell is growing, the DNA is uncoiled and aids in the
manufacture of proteins. Proteins are essential materials
required for the cell to carry out activities necessary for
survival.
When a cell is ready to divide, each strand of loosely coiled DNA
folds up further into a compact, X-shaped structure called a
chromosome.
Spread­out tangled DNA in the nucleus, which is called chromatin, tightens Centromere
into a compact coil. unreplicated
chromosome
chromosome
Chromosomes within the nucleus are found in pairs. Most human cells
have 23 pairs of chromosomes (i.e. 46 chromosones) including one
pair that determines gender.
Different species have different numbers of chromosomes
in their cells. ( pg 117). In sex cells, the number of
chromosomes is half, to 23, so that when sperm and egg
combine, the embryo produced has the correct number of 46
chromosomes.
Genes
• Found on chromosomes.
• Small segments of DNA located at specific places on a
chromosome.
• Store information needed to produce 90 000 to 100 000 proteins
used by body cells.
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• Genes can vary in length from hundreds to thousands of bases.
• The arrangement of bases will determine the protein produced.
• Each chromosome contains thousands of genes and therefore
contains the information to make thousands of different proteins.
• Proteins determine what body cells will become and how they will
function.
• Specialize cells will form tissues; tissues will form organs.
Only specific genes are read in each cell to produce specific
proteins. By making specific proteins, a cell becomes
specialized to carry out a specific function.
(Read “Wild, Weird, and Wonderful”, page 120)
Dec 1­9:56 PM
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