Topic 2- Cell structure Flashcards
Eukaryotic cells
Contain a nucleus and other membrane-bound organelles
eukaryotic vs prokaryotic cells
Prokaryotic cells are cells without a nucleus.
Eukaryotic cells are cells that contain a nucleus.
Eukaryotic cells have other organelles besides the nucleus, which allow eukaryotic cells to carry out more functions than prokaryotic cells can.
What three things do plant cells have that animal cells do not?
Cellulose cell wall, vacuole, chloroplasts
What are the two key differences between plant and fungal cells?
Their cell walls are made of chitin, not cellulose and they don’t have chloroplasts because they don’t photosynthesise
What are the chloroplasts like in algal cells?
What are the chloroplasts like in algal cells?
Which organelles have a double membrane?
Nucleus, chloroplasts and mitochondria
Description of cell surface membrane
Membrane found on the surface of animal cells and below the cell wall of other cells. Made mainly of phospholipids and protein
Function of cell surface membrane
Regulates the movement of substances into and out of the cell. It also has receptor molecules on it which allow it to respond to chemicals like hormones
Description of nucleus
Large organelle surounded by double membrane which contains pores. Contains chromosomes and one or more nucleoli
Function of nucleus
Controls the cells activities by controlling the transcription of DNA and contains instructions to make proteins. It also contains a nucleolus which makes ribosomes
Description of mitochondria
Oval shaped with a double membrane - the inner one is folded to form cristae. Inside is the matrix which contains enzymes controlling respiration
inner membrane is where oxidative phosphorylation occurs
Function of mitochondria
The site of aerobic respiration and responsible for producing most of the ATP in a cell. Active cells which require a lot of energy will have many of these
Description of chloroplasts
Found in plant and algal cells. Surrounded by a double membrane, with thylakoid membranes inside the organelle. Thylakoid membranes stack up into grana, joined by lamellae
Function of chloroplasts
The site where photosynthesis takes place. Some parts of photosynthesis happen in the grana, others in the stroma (a thick fluid found in chloroplasts)
Description of golgi apparatus
A group of fluid filled, membrane bound flattened sacs. Vesicles are often seen at the end of sacs
Function of golgi apparatus
Processes and packages new lipids and proteins
Description of golgi vesicles
Small fluid-filled sac produced by the golgi apparatus
Function of golgi vesicles
Stores and transports lipids and proteins made by the golgi apparatus either within the cell or out of the cell
Description of lysosomes
A round organelle surrounded by a membrane, with no clear internal structure. It’s a type of golgi vesicle
Function of lysosomes
Contain digestive hydrolytic enzymes called lysozymes. Can be used to digest invading cells or break down and work out components of the cell
Description of ribosomes
Small organelle found attatched to rough endoplasmic reticulum or free in the cytoplasm. Made from proteins and RNA, doesn’t have a membrane
Function of ribosomes
The site where proteins are made
Description of rough endoplasmic reticulum
A system of membranes enclosing a fluid filled space. The surface is covered in ribosomes
Function of rough endoplasmic reticulum
Folds and processes proteins that have been made at the ribosomes
Description of smooth endoplasmic reticulum
Similar to rough endoplasmic reticulum, but with no ribosomes
Function of smooth endoplasmic reticulum
Synthesises and processes lipids
Description of cell wall
Surrounds plant, algal and fungal cells. Made from cellulose in plants and algae, and chitin in fungi
Function of cell wall
Supports cells and prevents them from changing shape
Description of vacuole
Organelle in cytoplasm, contains cells sap. Surrounded by a membrane called a tonoplast
Function of vacuole
Helps to maintain pressure inside the cell and keeps it rigid, preventing wilting. Also involved in the isolation of unwanted chemicals
Prokaryotes definition
Single celled organisms
Difference between prokaryotic cells and eukaryotic cells
Prokaryotic cells are much smaller and simpler, has no nucleus
Capsule
Made of secreted slime and helps to protect the bacteria from attack by cells of the immune system
Cell wall in prokaryotes
Made of murein (a glycoprotein), this supports the cell and prevents it from changing shape
Cell surface membrane in prokaryotes
Like in a eukaryotic cell, this is made out of mainly lipids and proteins and it controls the movement of substances into and out of the cell
What three things do many prokaryotic cells have that eukaryotic cells do not?
One or more plasmids, a capsule surrounding the cell, one or more flagella
Plasmids definition
Small loops of DNA that aren’t part of the main circular DNA molecule which contain genes for things like antibiotic resistance, and can be passed between prokaryotes
DNA of a prokaryotic cell
No nucleus, instead they have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins
Process by which bacteria replicate
Binary fission
Stages of binary fission
- Circular DNA and plasmids replicate.
DNA loop only replicated once, but plasmids can be replicated lots of times.
- Cell gets bigger and the DNA loops move to opposite poles of the cell.
- Cytoplasm begins to divide and new cell wall begins to form
- Cytoplasm divides and two new cells are produced
each daughter cell has a variable number of copies of the plasmids and one copy of the circular DNA
What does each daughter cell from binary fission contain?
One copy of the circular DNA but can have a variable number of copies of the plasmids
Host cells
Cells in other organisms that viruses invade and reproduce inside of
Three main things to bacteria have that viruses don’t
Cell membrane, cytoplasm and ribosomes
Structure of virus
genetic material, capsid and attachment protein
Why do viruses not undergo cell division?
Because they are acellular and non-living
Viral replication
They attach to the host cell surface using their attachment proteins to bind to complimentary receptor proteins. They then inject their DNA or RNA into the host cell which uses its own ‘machinery’ to replicate the virus particles.
Why are antibiotics ineffective against viruses?
Antibiotics work by destroying bacterial cell membranes and bacterial replication, but viruses are acellular and do not have cell membranes, so antibiotics are ineffective
