Chapter 4

Questions:

1. Why do we need microscopes ?

Microscope is very important invention. It increases the ability of our vision because it magnifies very small objects. Due to this characteristic of microscopes we were able to go a step further in discovering the components of life such as cells atoms and even smaller particles. Before microscope we haven't had an idea of what are living organisms composed of.

2. What does the cytoskeleton do ?

Cytoskeleton is network of protein fibers that helps to organize and maintain structure of the cell and its organelles. We have 3 different types of protein fibers: Microfilaments (form a network that helps support the cell shape); Intermediate filaments (serve to reinforce the cell shape and to anchor certain organelles); Microtubules (they enable movement for cell).

3. What are the main differences between prokaryotic and eukaryotic cell ?

Prokaryotic cells are structurally simpler than eukaryotic cells. Prokaryotic cells lack nucleus, they don't have a membrane around surrounding DNA, ribosomes in prokaryotic cells are smaller than in eukaryotic. Eukaryotic cells on the other hand are more complex and those types of cells are the one found in many complex organisms like humans, plants, animals etc....

Eukaryotic cells have various organelles that maintain the functions of cell, for example : Golgi aparatus, ER, Lysosomes, Chloroplast etc....

Diagram :

On the left side of diagram is shown animal cell (prokaryotic cell) on the right is prokaryotic cell. This diagram shows the main differences between those two types of cells. As you can see prokaryotic cell is lacking nucleus and eukaryotic cell has a various number of organelles.

5facts:

Cilia and flagella move when microtubules bend, which enables the movement of cell

Plant's cell chloroplast are very important throughout the process of photosynthesis

Endosymbiosis it's a theory that mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cell.

Many organelles are connected through endomembrane system

We have two types cells that differ in their structures and that is prokaryotic cell and eukaryotic cell

Key terms :

chromosomes - carry genes made out of DNA

cytoplasm - entire region between the nucleus and the plasma membrane

cellular metabolism - many of the chemical activities of cell

organelles - membrane bounded structures perform specific functions in the cell

nucleus - contains most of the cell's DNA and controls the cell's activities by directing protein synthesis

Ribosomes - cellular components that carry out protein synthesis

Mitochondria - organelles that carry out cellular respiration in nearly all eukaryotic cells

Peroxisome - organelle that is not part of the endomembrane system; included in the breakdown of fatty acids

Lysosome - consists of digestive enzymes enclosed in membranous sac; digesting process

Vacuoles - membraneous sac with various functions such as hydrolitic (absorbs water)

Video :

Basic cell structure

Summarize :

This chapter is talking about the cell and it's basic structure. It describes all organelles and their function for example Nucleus is surrounded by porous nuclear envelope, the nucleus contains the DNA that carries the cell's hereditary blueprint. Also it divides the cell's organelles into group by their function and gives us the basic cell structure and types.