Cell Structure Flashcards
What is a eukaryotic cell?
Cell that contains DNA in a nucleus and is MEMBRANE-BOUND.
It is MULTICELLULAR.
Animal.
Plant.
Algae.
Fungi.
What is a prokaryotic cell?
Cell where DNA is free in the cytoplasm and is NOT membrane-bound.
It is UNICELLULAR.
Bacteria.
What are some examples of eukaryotes?
Animal cells
Plant cells
Algae
Fungi
What are some examples of prokaryotes?
Bacteria.
What are the differences between eukaryotes and prokaryotes?
Eukaryotes =
membrane-bound organelles
multicellular
DNA enclosed in nucleus
Prokaryotes =
not membrane-bound organelles
unicellular
DNA is free in cytoplasm.
Smaller
What is a multicellular organism?
Multicellular organisms use many different cells to function.
What is a unicellular organism?
Made up of only 1 cell that carries out all of the functions needed by the organism,
What is the cell membrane made out of?
Phospholipid bilayer.
Glycolipids
Glycoproteins
Cholesterol
Mainly lipids & protein.
What is the difference between a membrane and a cell-surface membrane?
A cell-surface membrane is the membrane surrounding the cell’s surface.
A normal membrane is the membrane around organelles?
What are cells made up of?
Organelles.
Remember… Year 9?
Cells, cells, they’re made of organelles!
What are the features of a nucleus?
NUCLEOPLASM =
contains chromosomes
Site of DNA synthesis
NUCLEOULUS =
(central region)
assembles ribosomes.
NUCLEAR ENVELOPE =
double membrane w/ nuclear pores to let substances exit/enter cell.
State the relationship between specialised cells and a system.
Specialised cells form…
Tissues that perform specific function that form…
Organs made of dif tissue types that form…
Organ systems
What is the function of cell-surface membranes?
Controls what molecules enters and leave the cell.
What is the structure and function of mitochondria?
= Structure =
Has DOUBLE MEMBRANE.
Inner membrane is folds to form CRISTAE (the inner layer of membrane inside)
Contains SHORT, CIRCULAR DNA.
Fluid MATRIX (gap inside mitochondria) contains enzymes involved in respiration.
= Function =
SITE of AEROBIC RESPIRATION to produce ATP (releases energy)
What is the structure and function of ribosomes?
= Structure =
Ribosomes have NO MEMBRANE.
Float freely in cytoplasm or attached to RER.
= Function =
Produces polypeptides from amino acids to form proteins.
What is the structure and function of a cell wall?
= Structure =
Made of CELLULOSE in plants & algae.
Made of CHITIN in fungi.
Made of MUREIN in prokaryotes.
= Function =
Supports cell providing rigidity and prevents them losing their shape.
Physical barrier against pathogens.
What organisms contain cell walls?
Plants
Bacteria
Algae
Fungi
What is the cell wall in plants made of?
Cellulose
What is the cell wall in fungi made of?
Chitin
What is the structure and function of the vacuole?
= Structure =
Single membrane called TONOPLAST.
Some pigments are found in the vacuole.
= Function =
Temporary food store containing sugars & amino acids.
Absorbs & hydrolyses harmful substances to detoxify cytoplasm.
When vacuole is full of fluid the cell becomes turgid (may burst)
Describe the structure and function of chloroplasts.
= Structure =
Contains DOUBLE MEMBRANE.
Small, flattened structure.
THYLAKOID membranes form stacks called GRANA (which contains chlorophyll)
Grana are connected by LAMELLAE (thin, flat pieces of thylakoid membrane)
= Function =
ABSORBS light for photosynthesis to produce carbohydrates.
Photosynthesis can happen in grana or stroma (body)
What key words are associated with chloroplast?
Thylakoid membrane
Double membrane
Grana / granum (singular)
Lamellae
Stroma
What key words are associated with the nucleus?
Double membrane
Nucleolus
Nucleoplasm
Nuclear envelope
What are the key words associated with mitochondria?
Matrix
Cristae
Circular DNA
Double membrane
What are the key words associated with rough endoplasmic reticulum?
Enclosed in a fluid-filled space.
HAS ribosomes.
Folds polypeptides into final 3D protein shape.
What are the key words associated with smooth endoplasmic reticulum?
Synthesis, processes, stores.
NO ribosomes
Steroids & lipids
Lipid synthesis
What does RER stand for?
Rough endoplasmic reticulum
Endon = within
Plasma = anything formed/moulded
Reticulum = small net
What does SER stand for?
Smooth endoplasmic reticulum.
What is the cell wall in prokaryotes made of?
Murein
What organelles contain DNA?
Nucleus
Mitochondria
Chloroplast
What feature makes an endoplasmic reticulum rough?
Having ribosomes.
Describe and explain the function of rough endoplasmic reticulum.
DESCRIBE…
RER is a system of membranes enclosing a fluid filled space.
Surface covered in RIBOSOMES.
EXPLAIN…
RER folds polypeptides into proteins made in ribosomes.
Describe and explain the function of smooth endoplasmic reticulum.
DESCRIBE…
Has NO ribosomes bound.
EXPLAIN…
Involved in synthesising, processing and storing molecules such as steroids (e,g, testosterone/oestrogen) and other lipids.
Stores lipids basically that combine with proteins to form lipoproteins.
Lipid synthesis.
Describe the structure and function of the golgi apparatus.
= Structure =
Group of fluid-filled membrane-bound FLATTENED discs.
= Function =
MODIFIES proteins - making them into glycoproteins/lipoproteins.
PACKAGES proteins into vesicles to transport them in and out of cell.
MODIFIES triglycerides.
What is the structure and function of lysosomes?
= Structure =
Round organelles surrounded by single membranes. It’s literally a ball that transports.
Type of Golgi vesicle.
= Function =
Contains ENZYMES to breakdown substances (e.g. worn out components of the cell)
What is a lysozyme?
Enzyme that breaks down some bacterial cell walls.
Describe how a lipoprotein is formed and transported out of the cell. [3 marks]
1# Ribosomes assemble amino acids to form polypeptides.
2# RER folds polypeptides into shape to form protein.
3# Lipids in SER and proteins in RER meet at Golgi apparatus.
4# Combines lipid & proteins to form lipoprotein.
5# Vesicle forms from Golgi which contains lipoprotein.
6# Vesicle travels to and fuses with plasma membrane. Exocytosis occurs.
What is exocytosis?
When molecules move out of the cell.
Describe the structure and function of a cell-surface membrane.
= Structure =
“Fluid mosaic” phospholipid bilayer with extrinsic & intrinsic proteins embedded.
= Function =
Separates cytoplasm from extracellular environment.
SELECTIVELY PERMEABLE to regulate transport of substances.
Involved in cell SIGNALLING / cell RECOGNITION.
Name one other substance other than the phospholipid bilayer that makes up a cell-surface membrane.
Glycolipids
Glycoproteins
Cholesterol
Explain the role of cholesterol in the cell-surface membrane.
A steroid molecule that connects with phospholipids and reduces fluidity of cell.
Explain the role of glycolipids in the cell-surface membrane.
Cell signalling & cell recognition (antigens)
Explain the role of glycoproteins in the cell-surface membrane.
Cell signalling & cell recognitions.
&
Binding cells together.
Describe the function of the nucleus.
Controls cell function =
gene expression determines…
specialisation,
mitosis,
site of mRNA transcription,
replication.
Contains DNA coiled around CHROMATIN to form chromosomes.
How are chromosomes formed?
DNA coils around CHROMATIN.
Describe the structure and function of ribosomes.
= Structure =
DO NOT have a membrane.
Float freely in cytoplasm or attached to RER.
= Function =
Where amino acids are joined together to make proteins (e.g. protein synthesis)
Explain some common cell adaptations.
Folded membrane / MICROVILLI =
Increases surface area for diffusion.
Many MITOCHONDRIA =
large amounts of ATP for active transport.
Walls 1 cell thick =
to reduce distance of diffusion pathway.
Is a virus particle larger or smaller than a bacterial cell?
Smaller.
Viruses are much smaller than bacteria.
Explain whether viruses are considered cells.
Viruses are NOT cells.
Because they cannot reproduce independently.
They can only reproduce inside a host cell using their enzymes.
Describe how a virus replicates. [3 marks]
1# Virus ATTACHES to the protein markers on a host cell using attachment proteins.
2# Virus INJECTS its genetic material into the HOST cell.
3# Host cell transcribes / translates the viral genes.
4# Protein forms NEW virus particles.
5# Virus particles BURST out of host cells and the host cell is destroyed.
Describe the structure and function of a virus. [4 marks]
A virus consists of…
Genetic material =
ALL viruses contain DNA / RNA.
Capsid =
Protein structure which contains the genetic material.
Attachment proteins =
Allow virus particles to attach and enter host cell.
Lipid envelope =
SOME viruses are surrounded by a lipid envelope formed from the host cell membrane.
What is the DNA in eukaryotes coiled around?
Histone proteins
How does DNA become coiled?
DNA coils around HISTONE proteins which makes the structure coiled.
This makes DNA compact and fit a lot of genetic information in a small volume.
What features do prokaryotic cells contain?
Plasmids
Single DNA molecule
Flagella
Slime capsule
Ribosomes
Cell membrane
Cell wall
Describe the structure and function of bacteria.
Plasmids =
Contains genetic information and codes for antibiotic resistance.
Single DNA molecule =
DNA loop - stores genetic info.
Flagella =
Helps with movement.
Slime capsule =
Outermost layer - sticks to cells - also protects cell from harm/chemicals.
Pili =
Some bacteria have pili which helps stick to surfaces.
Do ribosomes count as organelles?
No
because they are not membrane-bound.
