Chapter 1: Cell Structure Flashcards
- What are the two different types of cells?
Prokaryotes (Monera) and Eukaryotes (Everything else except Virus)
What’s the difference between Eukaryotes and Prokaryotes?
- Eukaryote cells are complex
- Prokaryote cells are smaller and simpler
What are the features of a prokaryote cell?
Organelles: Has no membrane bound organelles.
DNA: DNA strand is free and not enclosed in nucleus.
Nucleus: Absent in prokaryote.
Cell Wall: Made of peptidoglycan.
Endoplasmid Reticulum: No endoplasmid Reticulum.
Size: 0.5mm - 5mm
Ribosome: 70s
What are the features of eukaryotes?
Organelles: Has many membrane bound organelles i.e. mitochondria.
DNA: DNA is tightly coiled with histones (chromatin) enclosed in nucleus.
Nucleus: Present in eukaryote.
Cell Wall: If present, made of cellulose.
Endoplasmid Reticulum: Present, both and smooth.
Size: 40mm
Ribosomes: 80s (25mm)
What are the parts of a cell?
- Cell Wall
- Cell Membrane
- Nucleus
- Mitochondria
- ER
- Golgi Body
- Lysosome
- Ribosome
- Centriole (Centrisome)
- Chloroplast
- Vacuole
- Cytoplasm
What are the parts and fucntions of the nucleus.
The parts of the nucleus are:
- Double nuclear envelope
- Nuclear pore
- Nucleoplasm
- Nucleolus
Double Nuclear Envelope: Controls substances entering and exiting the nucleus.
Nuclear Pore: Normally plugged by RNA/protein complex, allow and control substances to move between nucleus and cytoplasm.
Nuclearplasm: Contains chromatin granules made of DNA and histones, sticky liquid medium where reactions take place.
Nucleolus: Makes ribsomes and RNA.
What are functions and features of a ribsome?
A very small organelle (80s/25mm) that consists of two subunits (small and large). It synthesizes protein.
What are the functions and feature of the Golgi Body?
Structure: A group of fluid filled, flattened sacs known as cisternae.
Function: Collects, processes and sorts molecules (protein) ready for transport in Golgi vesiles or to parts either in or out of the cell. Makes lysosomes.
What are the parts and functions of the mitochondria?
The mitochondria consists of:
- Double-membrane/cristae
- DNA Plasmid
- Matrix
- Phosphate Granule
Double membrane: Consists of outer and inner membrane, with the inner being folded into cristae which increase the surface area for chemical reactions
DNA Plasmid: Use their DNA to make proteins needed to synthesize energy.
Matrix: Contains enzymes i.e. decarboxylase which catalyses substances involved in respiration and has ribosomes.
Phosphate Granule: Regulate ion concentration in the cell.
What are the functions of the endoplasmid reticulum?
There are two types of endoplasmid reticulum:
- Rough Nedplasmid Reticulum (RER)
- Smooth Endoplasmid Reticulum (SER)
RER: Inter-connected system of flattened sacs and hollow tubes; studded in ribosomes. Covered in ribosomes, when protein chain is complete the RER pinches off vesicle which goes to cell membrane or Golgi body.
SER: System of inter-connected tubules with membranes enclosing a fluid filled space. Not covered in ribosomes, it makes lipids and steroids i.e. cholestrol and oestrogen and testosterone.
What is the structure and function of the lysosome?
Structure: Round organelle surrounded by membrane with protein and enzymes.
Function: Responsible for digestion of unwanted structures i.e. old organelles or whole cell.
What is the structure and function of the centriole?
Hint: think of microtubules
Microtubules:
- Made of alpha and beta tubulin, making dimers.
- Helical arrangement forms protofilament
- 13 protofilaments around a hollow core.
Structure: Nine groups of microtubules arranged in triplets, two of them perpendicular to one another. Found near nucleus.
Function: The centrioles region is known as the centrosome, which make up the spindle during nuclear division. In flagella and cillia, centrioles make up the basal bodies and microtubules that extend from it are essential for beating movements of these organelles.
What is the structure an the function of the chloroplast?
Structure: Has a double mebrane, and inner membrane is folded into a series of membrane-bound flattened sacs called thylakoid membranes stacked in grana and joined by lamellae. It also has a starch grain, lipid droplets all suspended in stroma.
Function: The thylakoid membranes have chlorophyll, which is the green pigment that is the site of photosynthesis. It also has starch grains and lipid droplets as an energy store.
What is the structure and function of the cell wall?
Structure: Cell walls are made of cellulose, and are “cemented” by the middle lamella between the different cell walls and have a gap between them known as the plasmodesmata.
Function (Cell Wall): Is permeable, protects the cell from i.e. bursting as well as forming part of a transport system that occurs between two cells.
Middle lamella: Pectin layer which cements two cell walls together and gives stability so they can form the plasmodesmata.
Plasmodesmata: Forms pathways between two adjacent cells, for the movement of water and solutes through plant structures.
What is the structure and function of the vacuole?
Structure: Consists of membrane known as tonoplast and inside is the cell sap which consists of salts, sugars, water and organic acids.
Function: Helps to maintain tugidity of the cell and pushes the cell membrane and cell wall, this is needed to keep the cell rigid.
What is the structure and function of the cell membrane?
Structure: Is flexible enough to move towards or away from the cell wall depending on the water potential inside the cell cytoplasm.
Function: Semi-permeable, controls movement of solutes in and out of the cell.
What is the structure and function of the cytoplasm?
Structure: A jelly-like substance that has most of the organelles suspended, as well as that many chemical reactions happen. Contains: water, enzymes, organelles, enzymes, salts and various organic molecules.
Function: Helps to move materials around the cell and dissolves cellular waste. Located inside is the cytoskeleton which provides mechanical and structural support for the cell.
Describe the internal structure of cillia/flagella.
Structure: They are surrounded by membrane and a ring of 9 pairs of protein microtubules and in the center a single pair of microtubules. (aka 9+2 arrangement)
Function: The microtubules allow the cillia to move, And in flagella i.e. sperm the microtubules contract to make the flagella move.
