Chapter 6 - The Cell

What do both prokaryotic and eukaryotic cells have?

plasma membrane, cytoplasm, DNA, ribosomes

What type of cells have organelles?

What are the levels of organization from smallest to biggest?

atoms, molecules, organelle, cell, tissue, organ, organ system, organism

All living things possess levels of:

organization

Cell

• smallest living port

• the simplest collection of matter that can live

• cell structure is correlated to cellular function

• an organism can be unicellular, or multicellular

Robert hook

• cells are very small; they were not discovered until microscopes were invented in the mid-seventeenth century

• in 1616, Robert hook examined cells on a piece of cork

• Anton van leevenhoek observed unicellular organisms

• advanced in microscopy led to cell theory

Principles of cell theory

• a cell is the most basic unit of life

• all living things are composed of cells

• all cells come from pre-existing cells

Are ribosomes considered living?

no; they can’t produce to make more

Prokaryotic cells

• bacteria

• first cells on earth

• simpler, smaller

• have no nucleus

• DNA is found in the nucleoid

• no membrane around the ribosomes

• has cell membrane

• some have cell walls and flagella

• the cell walls are not made up of cellulose

• made up of peptidoglycan

• do not have an endoplasmic reticulum because they are one cell big

Peptidoglycan

mesh-like macromolecule that forms the cell wall surrounding the cytoplasmic membrane of almost all bacteria

Eukaryotic cells

• first cells of this that appeared were unicellular

• larger than prokaryotes

• surrounded by cell membrane (double membrane)

• DNA is found in the nucleus

• has many membrane bounded organelles

• plant and animal cells

• nucleus is made up of the same material as the cell membrane; it has a double layer

Nucleus

• contains DNA

• chromatin is the complex of DNA

• nucleolus is a dark region where ribosomal DNA is produced

• ribosomal RNA is used to make ribosomes

• ribosomes can be found floating around in the cytoplasm or they can found on the rough endoplasmic reticulum

Nucleolus

primary site for the assembly and production for ribosomal DNA

Where can ribosome be found in a eukaryotic cell?

floating in the cytoplasm or on the rough endoplasmic reticulum

Does the smooth endoplasmic reticulum contain ribosomes?

no

Ribosomes

• site of protein synthesis

• can be found in floating freely in the cell (cytoplasm) or in the rough endoplasmic reticulum

Ribosomal RNA

forms the primary structural and catalytic core of ribosomes

Endoplasmic reticulum

contains continuous channels throughout the cell; has smooth and rough

Rough endoplasmic reticulum

• has ribosomes

• proteins are made here and can be transported out of the cell

Smooth endoplasmic reticulum

• synthesis of lipids and hormones

• does not contain ribosomes

• ex. glands

• cells in ovaries and testes are rich in ____ for their role in production of steroid s3x hormones

Golgi apparatus

• flattened sacs

• modify shape of protein and package proteins and lipids into vesicles which carry products to plasma membrane

• cis face - side where the proteins enter

• trans face - side where the protein leave

Cis face

side where the proteins enter in Golgi apparatus

Trans face

side where the proteins leave in Golgi apparatus

Lysosomes

• only found in animal cells

• cells cleanup crew

• contains digestive enzymes that break down old organelles, large particles

• low plt

• white blood cells that destroy bacteria

• when a cell does phagocytosis, it forms a food vacuole

  • a ____ fuses with the food vacuole and digests the molecules

• also use enzymes to recycle the cells own organelles and macromolecules by autophagy

Phagocytosis

the cellular process where a cell uses its cell membrane to engulf and digest large particles (cell eating); forms a food vacuole

Mitochondria

• cellular respiration takes place to make ATP

• our muscle cells are making and using 10 million ATP per second in one cell

• ATP (adenosine triphosphate) is the main energy source used by cells

• contains their own DNA

• predicted that it was free living and lived on their own millions of years ago

• have a double membrane

• reproduce similar to prokaryotes to make more ___

All living things need to make:

ATP

Endosymbiosis/Endosymbiotic Theory

• a smaller prokaryotic cell (mitochondria) was taken in by a large prokaryotic cell and this was beneficial to both cells leading to a cell with organelles (eukaryotic cells)

• mitochondrial DNA comes from the mother

• the mother gives the child the first organelles in the egg cell

• rather than being broken down by digestive enzymes, the engulfed prokaryotes provided their hosts with advantages from their special metabolic activities

Cell wall

• found in plants, fungi, some bacteria

• found in plant cells only

• outside plasma membrane and supports the cell

• plants are made up of cellulose

• fungi is made up of chitin

• bacteria is made up of peptidoglycan

Central vacuole

• stores water

• plant cell only

• gives the plant cell support when filled with water

• turgor pressure

Turgor pressure

the internal hydrostatic force exerted by water inside a cell that pushes the plasma membrane against the rigid cell wall

Chloroplasts

• found in plant cells

• does photosynthesis to make glucose

• contains chlorophyll and other pigments

• has a double membrane and their own DNA

• believed that it lived on their own before

Centrioles

• animal cells only

• are found by the nucleus and help the chromosomes (DNA) move during cell division

• made up of microtubules

Cytoskeleton

• a dense network of protein fibers the supports the organelles

• made up of microfilaments

Flagella

• long, singular appendages used for locomotion through liquid environments

• made up of microtubules (for eukaryotic)

• ex. human sperm

Cilia

• short, numerous appendages that enable cell movement and generate currents

• made up of microtubules

• located in nasal cavity; filters an swarms air

• located in fallopian tubes