Topic 3 (3.1 - 3.5 + 3.10) - Prokaryotes + Eukaryotes + Mitosis Flashcards
What is a eukaryotic cell
A cell that contains both a nucleus and membrane bound organelles
What is the range in size of eukaryotic cells
Most are between 1 - 100 micrometers
What is the cell surface / plasma membrane
A partially permeable selective barrier that is made of a phospholipid bilayer
Its found in ALL CELLS
What is the structure of the nucleus
It contains 2 membranes called the nuclear envelope (double membrane bound organelle
It has nuclear pores - allows the mRNA to leave
Nucleolus - Densely packed area of chromatin. rRNA (ribosomal RNA) is made here
Nucleoplasm - empty space in the nucleous
Chromatin - Double stranded + codes for proteins.
Strands of linear DNA are wrapped around histone proteins
What is the nucleus
A double membrane bound organelle, that holds the genetic material of a eukaryotic cell
What is the rough endoplasmic reticulum
An interconnected, single-membrane bound organelle
It is made of several sheets and tubes (cisternae), which connect it to the nucleus
Ribosomes are attached to it ( which is why its rough)
What does the rough endoplasmic reticulum do
It folds and processes proteins made at the ribosomes
Describe the structure of the rough endoplasmic reticulum
It is a single membrane with ribsomes attached.
It has a central lumen
It has cisternae
What are cisternae
They are flattened membrane vessicles
Ciaternae can be found in the Endoplasmic reticulum and the golgi apparatus
What is the smooth endoplasmic reticulum
A space which synthesises and processes, lipids and steroids
(e,g hormones)
Why is the smooth endoplasmic reticulum called smooth
As it has no ribosomes attached to it
What is the golgi apparatus
A single membrane-bound organelle made of several cisternae
It modifies and processes proteins (by adding carbohydrates)
It concentrates molecules (removes water)
It activates enzymes
It can also transport / package proteins and lipids in secretory vesicles
What does the golgi apparatus look like (how should it be drawn)
It is made up of at least 3 curved cisterna and is surrounded by vessicles
The cisternae get larger in size moving towards the trans face
What is the cis face of the golgi apparatus
the side that faces the rough endoplasmic reticulum
(receives transport vesicles)
What is the trans of the golgi appparatus
the side that faces the plasma membrane
(Releases secretory vessicles)
What are mitochondria
A double membrane bound organelle that is site of aerbic respiration in a cell
It is responsible for the production of ATP
What is the structure of a mitochondria
It has an outer membrane and an inner membane, with intermembranal space between the two
The inner membrane is folded into cristae
It contains ribosomes
It has a matrix (similar to the cytoplasm) - contains the ribosomes, proteins and enzymes
Mitochondial DNA
What is the structure of mitochondrial DNA
A circular loop of DNA
It doesnt contain Histone proteins
It has fewer genes
As it is a loop there are no exposed phosphate groups
What are ribosomes
Organelles that are the site of protein synthesis
What is the cristae
The folded inner membrane of a mitochondria
What are the size of eukaryotic ribosomes
80s
What are lysosomes
Single membrane sacs that contain hydrolytic (digestive) enzymes
What is apoptosis
Programmed cell death
Are lysosomes larger or smaller than most vesicles
Larger
What are centrioles
Microtubular structures that are found in right angles to each other
Each cell has a pair of centrioles
What is the purpose of centrioles
Forming spindle fibers during mitosis
Do centrioles have a membrane
No
What two ways can centrioles appear under a microscope
Two dark rectangular structures perpendicular to each other
A circular shape created by a repeated unit of 3 tibes connected tohether
What is a prokaryotic cell
A cell which contains no nucleus or no membrane bound organelles
What is the typical size of a prokaryote
0.5 - 5 micrometers
What organelles do MOST Eukaryotes always contain
Plasma membrane
Golgi apparatus
Mitochondria
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Lysosomes
Centrioles
Ribosomes
Nucleus
What are plasmids
Small loops of DNA (few genes) that contain accessory genes
What is a mesosome
Inward folds of the plasma membrane
Site of respiration
What are pilli
Short hair like structures
They stick to surfaces and transfer genetic material between cells
What is conjugation (prokaryotic cells)
The horizontal transfer of genetic material
What is a flagellum
A thread like structure that rotates to move a cell in liquids (propulsion)
What is the slime capsule
A secreted slime layer that protects prokaryotes from the imune system and prevents dehydration of the cell
What is the cell wall like in prokaryotes
It supports structure and shape
It is made of either Murein or Peptidoglycan
What are the size of ribosomes in prokaryotes
70s
What structres are always found in prokaryotes
Ribosomes
Cell wall
Plasma cell membrane
Circular DNA / nucleoid
How is DNA found in prokaryotes
It is circullar DNA found in an area called the nucleiod
It is fouund free floating in the cytoplasm
It has no histone proteins
What does the golgi apparatus do
- It processes and modifies proteins (adds carbohydrates) / lipids
- It concentrates proteins (removes water)
- It activates enzymes
- It packages enzymes ito vesicles
-It trims proteins (makes them smaller)
Are prokaryotes or eukaryotes always unicellular
Prokaryotes are always unicellular
How do you find image size using actual size and magnification
Image = actual x magnification
How do you calibrate an eyepiece graticule
Place the stage micrometer on the micrometer stage
Line up the divisions on the eyepiece graticule with those of the micrometer
Work out the length of one eyepiece graticule unit in micrometers
(Repeat for each magnification)
How do you measure the length of an object using an eyepiece graticule
Place a slide on the microscope slide
Measure the specimens length in eyepiece graticule lengths.
Multiply the length of one eyepiece graticule by the number the spwcimen is
Why can the same organelle look different under a microscope
They can be viewed at different angles, so their cross section is cut differently by the microscope.
This causes their shape to appear different
How do you calculate the length of 1 eyepiece graticule division
Find a pint to compare the eyepiece practice and micrometer
Multiply the number of stage micrometer divisions by the length of 1 division
Divide this value by the amount of eyepiece divisions (and convert to micrometers if necessary)
How do you move from milimeters micrometers
Multiply by 100
How are proteins transported around a cell
1)
They are translated in the ribosomes and enter the RER if they require modification
The 3D protein is then packaged into transport vesicles
2)
The vesicles fuse with the cisternae on the cis face of the golgi
After going through a process they are packaged into secretory vesicles which ‘pinch off’
3)
Exocytosis
Vesicles move to the plasma membrane and fuse to it
The protein is then secreted
Are all proteins secreted out of a cell
No some proteins remain in vesicles inside of the cell.
E.g lysosomes and channel / carrier proteins
What is the cell cycle
The steps a somatic cell goes through to grow and divide into two daughter cells
What happens in interphase
The cells size, mass and DNA increases
What happens in mitosis
Nuclear division, producing two nuclei
Why does mitosis occur
For growth
Repairing damaged tissues / replacing dead cells
Asexual reproduction
What are the three stages of interphase
G1 - growth phase 1
S - synthesis phase
G2 - growth phase 2
What occurs in G1
The cell grows (increase in cytoplasm and cell membrane)
Organelles duplicate
Other than to ensure the cells are identical, why would more mitochondria be produced in g1
Both interphase and mitosis occur a lot of energy
Having more mitochondria means more ATP can be produced
What occurs in S phase
DNA is replicated (from 2n to 4n)
Centrioles will double
Why is DNA replicated before mitosis occurs
To ensure there is enough DNA for the cell to divide and be genetically identical to the original cell
What happens in G2
The cell continues to grow
The cell is ‘checked’ to ensure there is enough dna / organelles for mitosis
What are the stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
What are the 3 stages in the cell cycle
Interphase
Mitosis
Cytokenisis
What happens in prophase
DNA condenses into chromosomes
Nuclear envelope and nucleolus disappear
Centrioles migrate to opposite poles and centrioles begin to form
What happens in metaphase
Chromosomes align at the equation of a cell (above each other)
Spindle fibers attach to the centromeres of the chromatids
What happens in anaphase
Spindle fibers contract and shorten splitting the centromere
Chromatids are pulled apart to opposite poles
What happens in telophase
The nuclear envelopes reform around the DNA
Nuclei reform
Spindle fibers break down
Chromosomes decondense
The cell begins to pinch
What happens in cytokenisis
The plasma membrane constricts around the center of the cell
A contractile ring forms and contracts to aid splitting (creating a cleavage furrow)
The cell splits producing two genetically identical diploid daughter cells
How do you calculate a mitotic index
(Number of cells in mitosis ÷ total number of cells) × 100
