Cytology

Cytology Cytology : study of the structure and function of cells. 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.

Prokaryotic Cells 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

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

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

Nucleotide 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.

DNA is made up of nucleotides DNA is made up of nucleotides. Each nucleotide has three parts: a deoxyribose molecule, a phosphate group, and a nitrogenous base. There are four different bases in DNA: adenine, guanine, cytosine, and thymine.

DNA Double Helix DNA is a double helix in which two strands are wound around each other. Each strand is made up of a chain of nucleotides. The two strands are held together by hydrogen bonds between adenine and thymine and between guanine and cytosine.

DNA Replication New Strand Original strand Nitrogen Bases Growth During DNA replication, the DNA molecule produces two new complementary strands. Each strand of the double helix of DNA serves as a template for the new strand. Replication Fork Replication Fork DNA Polymerase

Long chains of DNA form Chromatin. Short sections of DNA along a piece of chromatin form Genes. A gene will either produce or influence a specific trait in the offspring.

Chromatin Chromatin Nucleosome DNA double helix Coils Supercoils Eukaryotic chromosomes contain DNA wrapped around proteins called histones. The strands of nucleosomes are tightly coiled and supercoiled to form chromosomes. Histones

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.

Mitochondrion Mitochondria (plural) : is a membrane bound oval shaped organelle that function as the cell’s “power plant”. Creates the energy rich molecule called ATP (Adenosine Triphosphate). ATP is created through a process called Cellular Respiration which requires oxygen and therefore is an Aerobic process

Cellular Respiration C6H12O6 + 6O2 + enzyme 6CO2 + 6H2O + 36 ATP Only eukaryotic cells have mitochondria. The Cristae (inner membrane with finger-like projections) have enzymes attached to them where cellular respiration occurs. Mitochondria have their own DNA different from that of the nucleus. Biologists believe that a bacteria got trapped inside the early cell and evolved into this energy producing organelle. This mitochondrial DNA is very similar to bacterial DNA !

How do prokaryotic cells make ATP? They rely on a process called Fermentation. Fermentation is a simple Anaerobic (no O2) process that partially breaks down glucose to make SOME ATP. Example: Lactic Acid Fermentation which bacteria and humans perform. Glucose + Enzyme Lactic Acid + 2 ATP

Chloroplast Found only in plant cells. Contain the green pigment chlorophyll. They are involved with the process of Photosynthesis which takes place within these Thylakoid Membranes.

Photosynthesis 6CO2 + 6H2O + sun light C6H12O6 + 6O2 The glucose created from photosynthesis can now be broken down through Cellular Respiration to make 36 ATP. Chloroplasts also have their own DNA ?

Plant Cell Nucleolus Nucleus Smooth endoplasmic reticulum Nuclear envelope Ribosome (free) Rough endoplasmic reticulum Ribosome (attached) Cell wall Golgi apparatus Cell membrane Chloroplast Mitochondrion Vacuole

Animal Cell Smooth endoplasmic reticulum Nucleolus Nucleus Ribosome (free) Nuclear envelope Cell membrane Rough endoplasmic reticulum Ribosome (attached) Centrioles Golgi apparatus Mitochondrion

Another Animal Cell

Plant & Animal Cell Simulation Click on the title above and work through the plant and animal cell simulation.

Animal Cell Matching Activity Click on the title above and it will lead you to the animal cell website. Click on the “start activity” icon and let the fun start!

What’s The Difference? Animal Cell Plant Cell Do not have a cell wall Possess a cell wall made of cellulose Do not have plastids like chloroplasts Possess plastids like chloroplasts Possess centrioles used in cell division No centrioles but can still do cell division Possess small vacuoles Possess large vacuole 90% of cell’s volume Round to irregular in shape Rectangular in shape due to cell wall