OVERHEAD A

1
OVERHEAD A

• Name Date Period
• OBSERVATIONS Day 1
• In a space on your paper write down as many
  possible observations of the kernels traits for
  your teams ear of corn.
• HYPOTHESIS Day 1 -4
• A hypothesis is your best explanation or answer
  based on your observations, past experiences
  and/or background information. Remember that a
  hypothesis hasnt been tested so there are no
  correct answers, just logical ones.
• In the space below or on the back of your paper,
  write a hypothesis for the following focus
  question Whos Your Daddy (and Mommy)? In
  other words, what would the parent kernels look
  like, genotypically and phenotypically, if we
  could observe them?
• Be sure to consider how the kernels were formed.
  In order to do this each person on your team will
  need to find some background information. Find
  information using your Biology book and/or a
  internet search engine such as Google on how a
  kernel of corn is formed (corn reproduction). Be
  sure to include a written description as well as
  a diagram with labels.
• HYPOTHESIS FORMAT I think the parents look like
  _____________________ because __________(use your
  background information here)_________.

2
OVERHEAD B
Mom's seed (kernel)
Parental Generation (P)
Parental Generation (P)
Dad's seed (kernel)

• Female part, Ear
• Silks (Stigma Style or Pistil)
• Kernels (Ovary ovule, egg)

• Male part, Tassel
• Anthers
• Pollen (sperm)

CORN REPRODUCTION
First Filial Generation (F1)
3
OVERHEAD C

• Why are pollen (sperm) and eggs so important to
  sexual reproduction?
• hold genes that control traits (proteins)
• A sexually reproducing organism gets ½ of its
  genes from Dad and ½ from Mom

• How are sperm and egg (gametes) produced?
• Meiosis

• Why do you only get half of your genes from one
  parent?
• Meiosis

• Where are genes located?
• In the cells within the nucleus. Inside the
  nucleus the DNA is organized on structures called
  chromosomes. Sections of the chromosome or DNA
  that encode for proteins are known as genes.

4
OVERHEAD D
Corn cell
Chromatid
Centromeres
Centrioles
Kinetochores
DNA on Histones
Chromatin
Nucleus
10 pairs of chromosomes
Telomeres
Nuclear membrane
Where are the genes for Zea mays?
5
OVERHEAD E
A
A
A
A
B
B
b
b
d
d
d
d
Genes (Alleles) on a Homologous Pair of
Chromosomes
6
OVERHEAD G
Combinations of Alleles for a trait (Genotype)
7
OVERHEAD F
Remember A gene is a segment of DNA that encodes
for a particular protein.
Phenotype example
Dominant Gene (Allele)
Dominant Protein
Pigmented
Recessive Gene (Allele)
Recessive Protein
Non-functional protein, no pigment

• The gene may not produce a protein.
• The protein may be dysfunctional.
• The protein may have a different structure.

How do genes (alleles) control traits?
8
OVERHEAD H
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Interphase
cytokinesis
MEIOSIS for Zea mays (PMAT I)
9
OVERHEAD I
Prophase 2
Metaphase 2
Interphase
Anaphase 2
Telophase 2
cytokinesis
Interphase
MEIOSIS for Zea mays (PMAT II)
10
OVERHEAD J
DNA replication
produces an exact copy of the original chromatid.

Chromatid
Interphase and chromosome formation
11
OVERHEAD K
4 Sperm cells (in pollen) Haploid or N number of
chromosomes
4 Eggs (oocytes) Haploid or N number of
chromosomes

A
A
Polar Bodies
a
a
Sex cells (gametes) sperm and egg from a
heterozygous individual that has undergone Meiosis
12
OVERHEAD L
Sperm (pollen) Egg (oocyte)
Zygote
F e r t i l i z a t i o n
13
OVERHEAD M

• The Law of Segregation
• In each organism, a trait (for example
  pigment/color) is composed of two alternative
  states (for example, yellow or green). These
  alternative states are called alleles.
• Only one of the alleles is passed on to the
  offspring. Since an offspring gets an allele from
  each parent, it also has two alleles for each
  trait.
• Each allele has an equal chance of being passed
  on to the offspring.
• The two alleles do not blend, but remain
  distinct.
• There is a dominant/recessive relationship
  between the alleles. that is, if the two alleles
  are different, the dominant one will be
  expressed and the other will not.

Gregor Mendel The Father of Genetics