Chromosomes

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					         Chromosomes
 Identify how prokaryotes reproduce.
 Differentiate between a gene, a DNA
molecule, a chromosome, and a chromatid.
 Differentiate between homologous
chromosomes, autosomes, and sex
chromosomes.
 Compare haploid and diploid cells.
                       Vocabulary
Gametes – reproductive cells; sperm and eggs
Binary Fission – asexual reproduction in single celled organisms
where one cell divides into two cells of same size
Gene –a location on a chromosome that codes for a specific trait
Chromosome –a structure in the nucleus made of supercoiled
DNA and protein – DNA PRESENT AS CHROMOSOME ONLY BEFORE &
DURING CELL DIVISION
Chromatids – one of the two strands of a chromosome that is
visible during cell division
Centromere-the area that holds two sister chromatids together
Homologous Chromosomes-chromosomes with similar
sequence of genes that pair during cell division
                   Vocabulary
Diploid- describes a cell contains two sets of chromosomes
Haploid- describes a cell that contains one set of chromosomes
Zygote- a fertilized egg
Autosomes- chromosomes that DO NOT determine the sex
Sex Chromosomes- chromosomes that determine the sex
Karyotype- picture of individuals chromosomes used to diagnose
disorders

Trisomy- having three copies of a chromosomes instead of two
     Prokaryotic Cell Division
DNA is in the cytoplasm and is circular
Binary Fission – Asexual reproduction (a
single parent passes on exact copies of
DNA to its offspring)
Two stages
   1 – DNA is copied so each new cell has all of
    the information
   2 – a new cell membrane forms in the middle
    and the bacteria pinches in half.
     Prokaryotic Cell Division
Binary Fission Animation
Eukaryotic Cell Reproduction
Eukaryotic cells are much more
complicated than prokaryotic cells
Eukaryotic cells therefore contain a lot
more genetic information
   Chromosome Structure
ZOOM into DNA
                    Chromsome
Jumping
Jacks =
Sister Chromatids


Center of the
jumping jack
is the
CENTROmere
                          Genes
A gene is an address –
     a location on the
   chromosome and in
    the DNA sequence
      where info for a
      specific trait is
          located.
    Chromosome Numbers
Human cells (except for gametes) contain
23 PAIRS of chromosomes for a total of
46 chromosomes
The chromosomes differ in size, shape
and banding patterns
Each chromosome contains thousands of
genes that determine body structure and
function
   Homologous Chromosomes
  Each of the 23 pairs
  of chromosomes
  consists of two
  homologous
  chromosomes
A picture of the
  chromosomes is
  called a
  KARYOTYPE
 Autosomes/Sex Chromosomes
Autosomes – Pairs 1
  through 22
Sex chromosomes –
  Pair 23 XX (female)
  or XY(male)
        Haploid - Diploid
You get one of each chromosome from
your mother and the other from your father
to form your homologous chromosomes
All the cells of your body are diploid
(contain a pair of chromosomes) except
for your gametes (sex cells, ex: egg &
sperm)
Fertilization
            The gametes are each haploid
            so that after fertilization, the
            new cell (called a zygote) is
            diploid and contains a
            homologous chromosome
            pair for each of the 23 pairs.
          Human Fertilization



                     ZYGOTE – fertilized egg


GAMETES
Changes in Chromosome Number

Trisomy –
having three
copies of a
chromosome
rather than
two
Trisomy 21
= Down’s
Syndrome
Down’s Syndrome Symptoms
Individuals with Down Syndrome may not
experience all of the symptoms.
   decreased muscle tone at birth, asymmetrical or odd-
    shaped skull, round head with flat area at the back of
    the head, small skull, slanting eyes, small mouth with
    protruding tongue, broad short hands, single crease
    on the palm, retarded growth and development,
    delayed mental and social skills (mental retardation)
   inability to reach normal growth and development;
    Congenital heart defects in infants, early mortality;
    acute lymphocytic leukemia, and gastrointestinal
    abnormalities such as obstruction of the esophagus
    and obstruction of the duodenum.
      What’s in YOUR future
Vocabulary Quiz on Monday
Classwork/Homework:
   Create Index Cards on Vocabulary terms for
    Studying.
DON’T FORGET T/A PEOPLE…
RESEARCH PAPER IS DUE
MONDAY!!!!!!!!!!!!!!!

				
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posted:7/27/2012
language:English
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