Chapter 3 - Cell Structure Flashcards
What is a eukaryote
A cell with membrane bound organelles
What is a prokaryote
A cell with no membrane bound organelles
What organelles are found in an animal cell
Nucleus Cytoplasm Cell membrane RER SER Ribosomes Golgi Vesicles Mitochondria Lysosomes
What organelles are found in a plant cell but not in an animal cell
Chloroplasts
Vacuole
Cellulose cell wall
What are algae
Single called organisms
What organelles are found in algae
Same as plant cells
How are organelles of fungi different to algae
- Have no chloroplasts
- Cell wall made of chi-tin (kie-tin)
What are the functions of a nucleus
- Hold genetic material (where chromosomes are found)
- controls the cells activities
- Nucleolus makes ribosomes
What are the parts of a nucleus
Nucleolus
Chromatin
Nuclear envelopes
Nuclear pores
What is a rough endoplasmic reticulum
- network of fluid filled sacks
- usually attached to nucleus
- covered in ribosomes
What does the rough endoplasmic reticulum do
Modified and folds proteins
How is a smooth endoplasmic reticulum different from and rough
- Doesn’t have ribosomes
- Not attached to nucleus
What is a Golgi apparatus
A group of fluid filled sacks, that makes Golgi vesicles
What does the Golgi apparatus do
- Modify and package proteins and lipids
- Put then into vesicles for transport
- Make lysosomes
What do Golgi vesicles do
- Store and transport proteins and lipids
- can be transported out of the cell
What is a lysosome
A special type of vesicles
How is a lysosomes different to other vesicles
- They contain digestive enzymes called lysozymes
What do lysozymes do
Hydrolyse (break down) pathogens and old cell organelles
What are the structural features of mitochondria
- Outer membrane
- Cristae
- Matrix
What do mitochondria do
- The site of aerobic respiration
- Make ATP
What are the structural features of chloroplasts
- Thylakoids
- Grana (stack of thylakoids)
- Double membrane
- Stroma
- Starch grain
- Lamellae
What is the function of chloroplasts
- The site of photosynthesis
- Contain chlorophyll to absorb light energy
What the the function of a cell wall
To have a strong structure and so protect a cell and its organelles
What substance makes up a cell wall in plants and algae
Cellulose
What substance makes up a cell wall in fungi
Chitin
How can the structure of a vacuole be described
Has no fixed shape
What does a vacuole contain
Sugars and salts (cell sap)
What is the purpose of a vacuole
Keeps a cell turgid (not wilted)
What are ribosomes
Small proteins and RNA
What do ribosomes do
Make proteins
Where are ribosomes found
On RER or anywhere on the cell
What is the order of organisation of cells
Specialised cells
Tissue
Organ
Organ system
Give an example of an order of organisation of cells
Epithelial cell (ileum)
Epithelial tissue
Small intestine
Digestive system
What is a specialised cell
- A cell that has evolved adaptations specific to its function
What is tissue
A group of cells working together to perform a specific function
What is an organ
A group of tissues working together to perform a specific function
What is an organ system
A group of organs working together to perform a specific function
How is an epithelial cell specialised
They have microvilli, increasing their surface area so allowing more absorption
Explain the process of production and secretion of proteins
1) Nucleus contains gene for the protein (site of transcription, goes out nuclear pore)
2) Translation takes place on the ribosomes on RER
3) Protein transported to Golgi apparatus in a vesicle
4) Golgi modifies protein
5) Protein packaged into Golgi vesicle
6) Vesicle transported to cell surface membrane
7) Exocytosis- Vesicle fuses with membrane and ejects protein out of other side of membrane
What is a prokaryotic cell
Has no membrane bound organelles
Eg bacteria
What organelles can be found in a prokaryotic cell
- Loop of DNA
- Ribosomes
- cell wall
- cell membrane
- Cytoplasm
- Plasmids
- Flagella
- Capsule
Why is there a loop of DNA in prokaryotes
There is no nucleus
Where is poop of DNA found in prokaryotes
Free in the cytoplasm
What does a cell membrane do in a prokaryote
Controls what goes in and out of the cell
What does a cell wall do in a prokaryote
Provide strength and structure
What is the cell wall of a prokaryote made out of
Museum, a glycoprotein
What are plasmids
Small loops of DNA
What do plasmids do
Carry useful genes eg antibiotic resistance, and can be passed between bacteria
What does the flagella do
Act as a tail to help it move
What do the capsule do
sometimes Help to protect the bacteria cell from engulfment
How do prokaryotic cells divide
By binary fission
What is the process of a prokaryotic cell dividing known as
Binary fission
How is the way in which DNA is stored different in different types of cells
In prokaryotes, it is in a circular loop of DNA, and has no introns, histones or chromosomes
In eukaryotes it is found in the nucleus
How are the ribosomes different in different types of cells
In prokaryotes they are small, called 70s
In eukaryotes they are big, called 80s
How are cell walls different in different types of cells
In prokaryotes, glycoproteins are in cell walls and these are murein and peptidoglycan
In eukaryotes, animal cells don’t have cell walls, plant cells have cellulose and fungi have chitin
How do prokaryotes and eukaryotes differ with plasmids and capsules
All prokaryotes have plasmids, no eukaryotes do
Some prokaryotes have capsules, no eukaryotes do
Draw a virus and label it
Pentagon shape (capsid) Lines inside (genetic material) 4 legs (attachment proteins)
What do attachment proteins on virus’s do
Join virus to its host cell
What do it mean that virus’s are acellular
The don’t have their own cells, so are not living and can’t reproduce without use another living cell to do so
How do viruses reproduce
1) Attachment proteins bind to complementary receptor proteins on host cell (attachment proteins are specific to receptor proteins)
2) Virus injects it’s genetic material
3) It hijacks the host cell, using its organelles to reproduce more viruses
What are the methods of studying cells
Cell fractionation
Use of microscopes
What are the parts of cell franctionation
Breaking cells open
Filtering the solution
Ultra centrifugation
Explain why we break cells open as the first part of cell fractionation
Break them open
- Keep then ice cold (prevent enzyme activity)
- Keep them isotonic (prevents osmosis, organelles don’t change size
- Use buffer (keep the pH the same)
Explain why we filter the solution as part of cell fractionation
- Removes cell debris and whole cells
Explain the process and what happens as a result of ultra centrifugation of cells
- Spin year tube
- Heaviest organelles compressed into a pellet at the bottom
- Remaining liquid poured off
- Spin again
- Next heaviest removed
- Repeat
What are the three types of microscopes
Light/optical Scanning electron (SEM) Transmission electron (TEM)
State some advantages of light microscopes
- Easy to use
- Cheap
- Colour image produced
State advantages of SEM’s
- Better magnitude and resolution than light, as wave length is shorter than light
- Forms a 3D image
- Don’t need to slice a thin section (can observe living cells)
State advantages of TEM’s
- Even better magnification and resolution
- Allows internal structure to be seen
State disadvantages of light microscopes
- Lower magnification and resolution
- Can’t see smaller organelles (long wavelength)
Disadvantages of SEM’s
- Lower magnification and resolution than TEM’s
- Can’t see internal structures
Disadvantages of TEM’s
- Need a thin slice so can’t observe living cells
- Thin slices can cause artefacts
- Specimens need to be in a vacuum
- Image is not in colour
What is an artefact (microscopes)
Distortion of the image
What are the stages before and during mitosis
Interphase Prophase Metaphase Anaphase Telophase
What are the three stages of interphase, and what do the do
G1 - Gap 1, growth of organelles occurs
S phase - Synthesis, replication
G2 - Gap 2, continues to do its function
What happens in interphase
DNA replicates
Organelles replicate
Can’t see chromosomes
What happens in prophase
- Chromosomes condense (become visible, X shape)
- nuclear membrane breaks down
- centrioles move to poles
What happens in metaphase
- Chromosomes line up on the equator
- Spindle forms
- Spindle attaches to centromeres
What happens during anaphase
- Centromeres split
- What were sister chromatids are pulled apart as chromosomes to opposite poles
What happens during telophase
- Nuclear membrane reforms
What happens after just after mitosis
Cytokinesis
What is cytokinesis
Where the cell divides into 2
What is mitosis for, and what happens (short explanation)
Cell division to form 2 genetically identical daughter cells, for growth and repair
- 1 division
- 2 daughter cells
- 4 stages (PMAT)
Draw the cell cycle
Draw a circle
Just under a quarter should be nuclear division (mitosis/meiosis)
Small section of cytokinesis after this
All the rest made up by interphase
What is cancer
Uncontrolled cell division
How does cancer occur
- Mitosis, to divide cells, is controlled by genes
- If gene mutates, a cell can divide rapidly
- This will cause a tumour
How can cancer by treated
Controlling/restricting mitosis
What are ways that mitosis can be controlled or restricted to treat cancer
- Use of drugs (chemotherapy)
: to prevent DNA replicating
: to inhibit metaphase by interfering with Spindle fibres
Why can treatment of cancer be negative, but also why is this negative impact often limited
It can disrupt normal cells, however it is more effective against rapidly dividing cells
What is binary fission
Asexual reproduction/cell division of single cells led organisms
Eg bacteria
How does binary fission occur
- Circular loop of DNA and plasmids replicate
- Move to opposite ends of cell
- Cytoplasm divides to form 2 daughter cells
- Each has a single copy of circular DNA
