BIO 1404 Chapter 4 Notes

Biosciences Chapter 4 Notes: The Cell



Prokaryotic Cells: only the predominantly single- celled organisms of the domains
Bacteria and Archaea.
❖ Lacks a nucleus, or any other membrane- bound organelle.
❖ Prokaryotic DNA is found in a central part of the cell, called the nucleoid.
➢ Nucleoid: central part of a prokaryotic cell in which the chromosome is
found.
❖ Have a cell wall and many are surrounded by a polysaccharide capsule.
➢ Cell Wall: rigid cell covering made of cellulose that protects the cell,
provides structural support, and gives shape to the cell.
■ The cell wall acts as an extra layer of protection, helps the cell
maintain its shape, and prevents dehydration.
❖ Some prokaryotes have flagella, pili or fimbriae.
➢ Flagella: long, hair- like structure that extends from the plasma membrane
and is used to move the cell.
➢ Pili are used to exchange genetic material during a type of reproduction
called conjugation.
❖ DNA is organized into a single circular chromosome
Eukaryotic Cells: cells of animals, plants, fungi and protists are all eukaryotes.
❖ Have a membrane- bound nucleus
❖ Numerous membrane- bound organelles such as the endoplasmic reticulum, Golgi
apparatus, chloroplasts, mitochondria, and others
❖ Two or more chromosomes
❖ DNA chromosomes are linear
Eukaryotic and Prokaryotic Cells Similarities:
1. A plasma membrane ( an outer covering that separates the cell’s interior from its
surrounding environment)
2. Cytoplasm, (consisting of a jelly-like cytosol within the cell in which other cellular
components are found)
3. DNA ( the genetic material of the cell)
4. Ribosomes ( synthesize proteins)

The Plasma membrane controls the passage of organic molecules, ions, water and
oxygen into and out of the cell. Wastes ( such as carbon dioxide and ammonia) also leave the
cell by passing through the plasma membrane.
Chromosomes are structures within the nucleus that are made up of DNA, the hereditary
material, and protein. The major protein associated with DNA is called histones.

Chromatin: protein DNA complex that serves as the building material of chromosomes. It
makes up chromosomes both when condensed and decondensed.

, Ribosomes: cellular structure that carries out protein synthesis.
❖ Ribosomes, which are large complexes of protein and RNA, consist of two subunits,
aptly called large and small
❖ Ribosomes receive their orders for protein synthesis from the nucleus where DNA is
transcribed into messenger RNA (mRNA) The mRNA travels to the ribosomes, which
translate the code provided by the sequence of nitrogenous bases in mRNA in a specific
order of amino acids in a protein.
Mitochondria ( singular= mitochondrion): cellular organelles responsible for carrying out
cellular respiration, resulting in the production of ATP (adenosine triphosphate) , the cell’s main
energy- carrying molecule. Often called “powerhouses” or “energy factories”
❖ ATP represents the short-term stored energy of the cell.
❖ Cellular respiration is the process of making ATP using the chemical energy found in
glucose and other nutrients.
❖ Muscles cells have a very high concentration of mitochondria that produce ATP.Your
muscle cells need a lot of energy to keep your body moving.
❖ When your cells don’t make get enough oxygen, they do not make a lot of ATP
❖ Mitochondria are oval-shaped, double membrane organelles that have their own
ribosomes and DNA.
➢ Each membrane is a phospholipid bilayer embedded with proteins.
■ The inner layer folds called cristae
■ The area surrounded by the folds is called the mitochondrial matrix.



● The cristae and the matrix have different roles in cellular
respiration.
Cellular Respiration: is a set of metabolic reactions and processes that take place in the cells
of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP)
and then release waste products.
❖ C6H12O6 + 6O2 --> 6CO2 + 6H2O
❖ A catabolic pathway
❖ Oxygen is consumed as a reactant along with organic compounds.
❖ Involves three stages:
➢ Glycolysis
➢ Krebs Cycle
➢ Electron Transport Chain
❖ How do we get energy from ATP?
➢ By breaking the high-energy bonds between the last two phosphates in
ATP.
❖ NADH and FADH2
➢ NAD+ traps electrons from glucose to make NADH (energy stored)
➢ Similarly, FAD+ stores energy as FADH