AS Cell Structure and Division Flashcards
Name the organelles present in both animal and plant cells and the 3 organelles only present in plant cells
Both:
- Cell surface (plasma) membrane
- Nucleus
- RER - rough endoplasmic reticulum
- SER - smooth endoplasmic reticulum
- Lysosomes
- Ribosomes
- Golgi apparatus
- Golgi vesicles
- Mitochondria
Plant cells only:
- Chloroplasts
- Vacuole
- Cell wall with plasmodesmata
Describe the structure of algal and fungal cells compared to plant cells
Algal cells:
- Same organelles as plant cells
Fungal cells:
- Cell walls made of chitin (not cellulose)
- Don’t have chloroplasts (don’t photosynthesise)
Describe the structure and function of the cell-surface membrane
Structure:
- Found on surface of animal cells and inside the cell wall of other cells
- Mainly made of lipids and proteins
Function:
- Regulates movement of substances in and out cell
- Has receptor molecules - respond to chemicals
Describe the structure and function of the nucleus
Structure:
- Surrounded by nuclear envelope - contains pores
- Contains chromosomes made from protein-bound linear DNA
- Contains nucleolus
Function:
- Controls cell activities - controlling transcription of DNA
- DNA contains instructions to make proteins
- Pores allow substances (RNA) to move in and out
- Nucleolus makes ribosomes
Describe the structure and function of mitochondria
Structure:
- Double membrane - inner one folds to form cristae
- Contains matrix - has enzymes for respiration
Function:
- Site of aerobic respiration - ATP produced
- Found in active cells - require lots of energy
Describe the structure and function of chloroplasts
Structure:
- Flattened structure in plant and algal cells
- Double membrane - contains thylakoid membranes
- These stack up into grana - linked together by lamellae
Function:
- Site of photosynthesis
- Some occurs in grana and some in stroma
Describe the structure and function of the Golgi apparatus
Structure: - Fluid-filled, membrane-bound flattened sacs - Vesicles next to apparatus Function: - Processes and packages new lipids - Makes lysosomes
Describe the structure and function of the Golgi vesicles
Structure:
- Fluid-filled sac in cytoplasm
- Produced by Golgi apparatus
Function:
- Stores lipids and proteins made by Golgi apparatus
- Transports them out of cell via plasma membrane
Describe the structure and function of lysosomes
Structure: - Round, surrounded by membrane - No internal structure - Type of Golgi vesicle Function: - Contains digestive enzymes - lysozymes - These digest invading cells or break down worn out components of cell
Describe the structure and function of ribosomes
Structure: - Very small - no surrounding membrane - Free floats in cytoplasm or attached to RER - Made up of proteins and RNA Function: - Site of protein synthesis
Describe the structure and function of the rough endoplasmic reticulum (RER)
Structure:
- System of membranes enclosing fluid-filled space
- Surface covered with ribosomes
Function:
- Folds and processes proteins made at the ribosomes
Describe the structure and function of the smooth endoplasmic reticulum (SER)
Structure: - System of membranes enclosing fluid-filled space - No ribosomes Function: - Synthesises and processes lipids
Describe the structure and function of the cell wall
Structure:
- Rigid structure surrounding plant, algal and fungal cells
- Plants and algae - made mostly of cellulose
- Fungi - made of chitin
Function:
- Supports cells - stops them changing shape
Describe the structure and function of the vacuole
Structure:
- Found in cytoplasm of plant cells
- Contains cell sap - solution of sugars and salts
- Surrounding membrane - tonoplast
Function:
- Maintains pressure and keeps cell rigid
- Stops plant wilting
- Involved in isolation of unwanted chemicals inside the cell
Explain why the structure of specialised cells may vary in different parts of the body
- Specialised cells carry out specific functions
- Cell structure helps it carry out its function
- If a cell requires lots of energy, it will need more mitochondria. If it requires lots of proteins, it will need more ribosomes
How are specialised cells organised?
- Specialised cells grouped together - form tissues
- Tissue - group of cells working together to perform a particular function
- Different tissues work together - form organs
- Different organs make up organ system
Name the organelles present in prokaryotic cells
- Plasma membrane
- Ribosomes (smaller than in eukaryotes)
- Cell wall
- Plasmids
- Circular DNA
- Flagellum
- Capsule (some prokaryotes e.g. bacteria)
Describe the structure and function of the flagellum
Structure:
- Long, hair-like structure
Function:
- Rotates to make the cell move
Not all prokaryotes have them - some have more than one
Describe the structure of circular DNA
Structure:
- No nucleus - DNA free floats in cytoplasm
- One long coiled-up strand
- Not attached to any histone proteins
Describe the structure and function of plasmids
Structure:
- Small loops of DNA
Function:
- Contain genes for things like antibiotic resistance - can be passed between prokaryotes
Not always present in prokaryotic cells - some have several
Describe the structure and function of the cell wall
Structure:
- Made of a polymer called murein (a glycoprotein)
Function:
- Supports cell and prevents it from changing shape
Describe the structure and function of the capsule
Structure:
- Made up of secreted slime
Function:
- Helps protect bacteria from attack by cells of the immune system
Describe the structure and function of viruses
Structure:
- Smaller than bacteria - (HIV about 0.1um across)
- No plasma membrane, cytoplasm or ribosomes
- Contain core of genetic material - DNA or RNA
- Capsid - protein coat around core
- Attachment proteins stick out from capsid - let virus cling on to host cell
All viruses invade and reproduce inside host cells
Describe the process of binary fission
Cell replicates genetic material before splitting into 2 daughter cells
- Circular DNA and plasmids replicate
- Cells expands - DNA loops move to opposite poles
- Cytoplasm begins to divide - new cell wall forms
- Cytoplasm divides - 2 daughter cells produced - each with one copy of circular DNA and variable plasmids