Eukaryotic Cell Structure Flashcards
What are the 2 types of cells?
Prokaryotic and Eukaryotic
What are the characteristics of prokaryotic cells?
- No membrane bound nucleus or *organelles
- Single celled
- Simpler internal structure - single undivided area called cytoplasm
*How much of a prokaryote is inside the prokaryotic cytoplasm?
Everything inside the plasma membrane
Describe the prokaryotic cytoplasm.
Internal fluid made up of cytosol and cytoskeleton
Where do all of the metabolic reactions in a prokaryote occur?
In the prokaryotic cytosol
What is the cytosol composed of?
Water, ions and organic molecules
What is the cytoskeleton?
A network of fibres inside the cytoplasm
What organisms are classed as eukaryotes?
Animals, plants, fungi, single-celled protoctista
Define what a eukaryotic cell is.
A cell with a membrane bound nucleus and organelles
*How much of a eukaryote is inside the eukaryotic cytoplasm?
Everything between the plasma membrane and nuclear envelope
Define organelle.
What do organelles provide?
Membrane-bound compartments with varying functions inside eukaryotic cells
Organelles provide distinct conditions for different reactions
Define metabolism
Sum of all chemical reactions that occur within each cell of an organism that provide energy for vital processes and synthesis of new organic material
What 2 processes does metabolism involve? Define each of them.
- Anabolism - Reactions of metabolism that construct molecules from smaller units. These reactions require energy, which comes from the hydrolysis of ATP
- Catabolism - Reactions of metabolism that break molecules down into smaller units. These reactions release energy.
What are the 2 very basic characteristics of a plasma membrane
Selectively permeable
Controls movement of substances into and out of the cell and organelles
Fragile
What does the nucleus contain?
Coded genetic information in the form of DNA
What is the function of DNA
Direct protein synthesis
What surrounds the nucleus?
What is the function of this structure?
- Double membrane nuclear envelope
2. Protect the nucleus from damage in the cytoplasm
What does the nuclear envelope contain?
What is the function of this structure?
- Nuclear pores
2. Allow molecules to move in and out of the nucleus
Why can’t DNA leave the nucleus? How does DNA solve this issue?
DNA itself is too large to fit through the nuclear pores.
To get over this issue, DNA is transcribed into smaller RNA molecules, which can then leave through the pores
How are chromosomes formed?
- DNA associates with histones (proteins that form a complex with DNA called chromatin) to form chromatin (Uncondensed DNA in a complex with histones)
- Chromatin coils and condenses to form chromosomes (Structures of condensed and coiled DNA in the form of chromatin)
Where is the nucleolus?
Inside the nucleus
What is the function of the nucleolus?
Produce ribosomes
What is the nucleolus composed of?
Proteins and RNA
What is the function of RNA in the nucleolus?
RNA is used to produce ribosomal RNA (rRNA), which is then combined with proteins to form ribosomes
Describe the structure of the mitochondria.
- Double membrane
* Inner membrane = highly folded to form cristae
Define cristae
Fold of inner mitochondrial membrane.
Increases SA for electron transfer chain to occur.
What is the function of cristae membranes in terms of what they contain?
Contain enzymes used in aerobic respiration
Can mitochondria produce their own enzymes?
Yes
Can mitochondria reproduce themselves?
Yes
Do mitochondria contain DNA? Where is it located?
Yes - mtDNA - present in the matrix
What are vesicles?
Membranous sacs with storage and transport roles
Describe the structure of vesicles
Single membrane with fluid inside
What are lysosomes? What do they contain?
Specialised vesicles that contain hydrolytic enzymes
What is the function of lysosomes?
- Break down waste material in cells
- Break down pathogens ingested by phagocytes
- Apoptosis - programmed cell death
What is the cytoskeleton
A network of fibres present throughout the cytoplasm
What are the 4 functions of the cytoskeleton?
- Maintains the shape and stability of cells
- Holds organelles in place
- Controls cell movement
- Controls movement of cells within organelles
What are the 3 components of the cytoskeleton?
- Microfilaments
- Microtubules
- Intermediate fibres
Describe the structure of microfilaments.
Contractile fibres formed from actin
What is the function of microfilaments?
- Cell movement
* Cell contraction during cytokinesis (where a eukaryotic cytoplasm divides into 2 daughter cells)
What is the function of microtubules?
- Determine cell shape
* Act as tracks for movement of organelles e.g. vesicles
What do microtubules form?
Spindle fibres
What is the function of intermediate fibres?
- Maintain mechanical strength of cell
* Maintain cell integrity
What are centrioles?
Components of the cytoskeleton of eukaryotes, (apart from flowering plants and most fungi) composed of microtubules
What do 2 centrioles form?
Centrosome
Where are flagella and cilia found?
Extending from some cell types
What is the function of flagella?
- Cell motility
* Sensory organelles
What are the 2 types of cilia?
Mobile and stationary
What part of the body do sensory cilia have a role in?
Sensory organs e.g. nose
What is the function of mobile cilia?
Beat in a rhythmic manner, creating a current which causes adjacent fluid and objects to move
Give 2 anatomical examples and functions of cilia.
Present in trachea - move mucus away from lungs
Present in fallopian tubes - move egg cells from ovary to uterus
Describe the structure of 1 cilium.
2 central microtubules surrounded by 9 pairs of microtubules arranged in a wheel, known as the 9+2 arrangement
What is the endoplasmic reticulum?
A network of membranes enclosing flattened sacs called cisternae
What is the endoplasmic reticulum connected to?
Outer membrane of the nucleus
What does the smooth endoplasmic reticulum have a role in?
Synthesis and storage of lipids and carbohydrates
What’s the structural difference between the SER and RER?
RER has ribosomes bound to the surface
What does the rough endoplasmic reticulum have a role in?
Synthesis and transport of proteins
Where are ribosomes located?
Free floating in cytoplasm or attached to RER.
Also found in mitochondria, chloroplasts and prokaryotes.
Do ribosomes have a membrane?
No
What are ribosomes made up of? Where does this originally come from?
RNA - made in nucleolus
Describe the structure of the Golgi apparatus.
Formed from an interconnected network of cisternae/flattened membranous sacs
What is the function of the Golgi apparatus?
Modification and packaging of proteins
State the process of protein synthesis.
*Spec says it’s not needed
- Proteins are synthesised on ribosomes bound to EP
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