Chapter 4: A Tour of the Cell Flashcards
The Cell Theory
- All organisms are composed of one or more cells.
- The cell is the smallest, most basic unit of structure and organization in all organisms.
- All Cells arise from pre-existing, living cells. (offspring)
Cell Size Must…
- Be large enough to house DNA, proteins, and structures needed to survive and reproduce.
- Remain small enough to allow for a surface-to-volume ratio to allow adequate exchange with the environment.
- Increase surface area (more surface area makes the cell more efficient)
What are the five basic structures of the cell?
- Plasma Membrane
- Cytosol
- Nucleus or Nuclear Area/Body
- DNA
- Ribosomes
Cytosol
Semifluid substance (cytoplasm) is the fluid-filled space, the cell’s entire contents between the plasma membrane and the nucleus.
Plasma Membrane
Controls what substances enter and exit the cells.
Nucleus or Nuclear Area/Body
It contains DNA.
DNA
Chromosomes (carry genes)
Ribosomes
synthesizes proteins
What are the two types of cells?
Prokaryotic and Eukaryotic
Prokaryotic cells are…
All single-celled
Have NO nucleus
NO organelles
Eukaryotic Cells are…
Single-cell protists and multicellular organisms.
Do have organelles
Have a nucleus present.
Eukaryotic cells are characterized by having…
- DNA in the nucleus that is bounded by a membranous nuclear envelope.
- Membrane-bound organelles (Organized and have double membranes)
- Cytoplasm in the region between the plasma and the nucleus.
The Endosymbiotic Model or Theory
The folding of membranes increases surface area, and cells engulf other cells but do not destroy them because they have food or small cells get protection.
The theory explains how eukaryote cells could have evolved from prokaryotic cells.
Three parts of the plasma membrane
- Phospholipids
- Cholesterol
- Proteins.
The head of the of the phospholipids are…
Hydrophilic (polar)
The legs of the phospholipids are…
Hydrophobic (nonpolar)
Phospholipids
- Form a two-layer sheet.
- Amphiphilic
Cholesterol (in the plasma membrane)
- Helps to stiffen the plasma at high temperatures.
- It helps maintain fluidity at low temperatures.
Proteins (in the plasma membrane)
They help perform specific reactions and allow molecules to enter the cell.
Glycocalyx (in the plasma membrane)
Used for cell recognition.
Nucleus
- The cellular control centers.
- Contains the genetic material information of the cell.
- DNA never leaves the cell.
Nuclear Envelope
Double membrane (almost like the plasma membrane but for the nucleus)
Nuclear Pore
Allow passage ONLY for rRNA, mRNA, and proteins.
Nucleolus
Darkest part of the nucleus. Synthesizes rRNA (which makes ribosomes)
Chromatin
Contains Chromosomes and is surrounded by nucleoplasm.
Ribosomes
Synthesizes PROTEINS using mRNA.
Ribosomes are composed of…
2 subunits.
Small and large subunits.
Where are ribosomes located in the cell?
Can be free in the cytoplasm attached to the rough ER.
Why are ribosomes not organelles?
Ribosomes are not organelles because it does not have a double membrane.
Smooth Endoplasmic Reticulum
synthesizes LIPIDS.
Stores calcium and detoxes.
A large number of smooth ERs are in organs such as the liver and kidneys
Rough Endoplasmic Reticulum
Contains RIBOSOMES
Helps FOLD proteins
Creates membrane
Polypeptides
chain of amino acids (proteins)
Golgi Apparatus
Finishes, sorts, and ships cell products in the cytoplasm. These products turn into vesicles, to be either used by the cell or expelled outside the cell.
Vesicles
membrane-bound “balloons” that transport and store substances in the cells. (found in animal cells)
Vacuole
A small membrane-bound cell organelle helps ISOLATES WASTE PRODUCTS. Stores waste and kicks our access water out.
Lysosomes
Sac of enzymes that digests within the cell. Recycles or destroys damaged organelles.
Lysosomes contain…
Hydrolytic digestive enzymes (low pH) that will break down stuff in the cell to be used.
The various organelles of the endomembrane system are…
interconnected structurally and functionally.
Peroxisomes
Breaks down lipids and free radicals.
Detox alcohol.
Oxidase produces hydrogen peroxide, which is broken down via catalase to water and oxygen.
Mitochondria
Harvest energy from food.
CARRY OUT CELLULAR RESPIRATION
Inner membrane (in the mitochondria)
contains proteins for ATP synthesis
ATP
Adenosine Triphosphate
Cristae (in the mitochondria)
folds.
Matrix (in the mitochondria)
contain mitochondrial DNA, ribosomes, and enzymes. (that will help break down carbs/molecules)
Cytoskeleton
The cell’s internal skeleton helps organize its structure and activities.
The cytoskeletons function
- Maintenance of cell-type anchorage.
- Movement.
- Amoeboid Movement
- Muscle Contraction
Three types of cytoskeletons.
Microfilament
Intermediate Filament
Microtubles
What is microfilament made up of?
Actin Subunit
What is intermediate filament made up of?
Fibrous subunits.
What is microtubules made up of?
Tubulin subunits.
Cilia and flagella move when…
Microtubules bend
Cilia
Short
Numerous
Wave like motion
Flagella
Long
Typically, singular.
Can only move forward.
The Extracellular Matrix of cells functions in….
support and regulation.
Three types of cell junctions
Tight junction
Anchoring Junction
Gap Junction
Tight junction
PREVENT LEAKAGE of extracellular fluid across a layer of epithelial cells.
Bring cells closer than adhesion junctions.
Create IMPERMEABLE BARRIER, bound together by specific proteins.
Anchoring Junction
FASTEN CELLS TOGETHER INTO SHEETS.
(Adhesion) movements and FLEXIBILITY .
Mechanically attaches adjacent cells.
Gap Junction
CELL COMMUNICATION.
Channels that allow molecules to flow between cells.
Allows tiny molecules to flow between cells.
Allows substances to flow from cell to cell through membrane channels.
Anchoring Junction is most common in…
Skin, uterus, and stomach.
Gap Junctions are most common in…
Cardiac muscles, embryonic cells, and liver cells,
Desmosomes is also called
Anchoring junctions.
Gap junctions is also called
Communicating junctions.
Plant cells also have….
Central Vacuole
Chloroplast
Cell Wall
Plasmodesmata
Central Vacuole
Stores water, solutes, and waste.
Important for growth and rigidity.
Function in the general maintenance of the cell.
Chloroplast
CONDUCT PHOTOSYNTHESIS, where the green pigment chlorophyll captures the energy from sunlight.
Depending on the species some have only one and others have hundreds.
Convert energy to chemical energy with SUGARS.
Cell Wall
Made of cellulose
Located outside the cell membrane.
Provides structural support and protection.
Sometimes acts as a filtering mechanism.
Plasmodesmata
Allows for the exchange of solutes and cell communication.
