Introduction to cytology

1. Objectives:
1. What is Cytology?
2. Explain how prokaryotic & eukaryotic cells
differ.
3. What is DNA?
4. Identify the parts and function of the
Nucleus.

2. It is the study of the structure and function of cells.
The cell is the basic structural and functional unit of
life so therefore cytology is the fundamental most
important topic in all of biology.

4. Cytoplasm : area of space outside the nucleus;
contains the organelles & cytosol.
Organelles : are tiny structures in the cytoplasm
which perform various jobs for the cell.
Cytosol : is the fluid part of the cytoplasm.

5. They lack a nuclear
membrane as well any
other membrane covered
organelles in their
cytoplasm.
Considered to be
“Primitive Cells”
Example : Bacteria & Blue-
Green Algae

6. They possess a nuclear
membrane as well as
membrane bound
organelles in their
cytoplasm.
Example : Plant &
Animal Cells

7. is the computer or control center of the cell.
contains the genetic material of life DNA
(Deoxyribonucleic acid).
discovered by James Watson, Francis Crick, &
Rosalind Franklin (1953).
a DNA molecule consists of nucleotides connected
together.

8. A nucleotide consists of a :
1. Phosphate group
2. Deoxyribose sugar
3. Nitrogen base: 4 types
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
DNA consists of two nucleotide
chains connected together.
A & T always pair up, while
C & G do the same.

9. DNA Double Helix

10. Your genetic code is found in groups of 3
rungs in the ladder called DNA triplets
AA
TT
GG
TT
AA
CC
5’
3’
5’
3’

12. Complete the worksheet entitled “ODE to DNA” .

14. Long chains of DNA form
Chromatin.
Short sections of DNA
along a piece of chromatin
form Genes. Human
genome contains about
30,000 genes!
A gene will either produce
or influence a specific trait
in the offspring.

15. Chromatin
Chromatin
Supercoils
Nucleosome
DNA
double
helix
Histones
Coils

16. Nucleolus / Nucleoli (plural) : a dark spherical
structure that is the site of ribosome formation.
Ribosomes and other important chemical messages
leave the nucleus through the Nuclear Pores. The
membrane around the nucleus is called the Nuclear
Membrane or Envelope.