Cells Flashcards
What does the endosymbiotic theory state?
Some organelles in eukaryotic cells were once prokaryotic microbes
This theory explains the origin of mitochondria and chloroplasts.
What is believed to be the first eukaryotic cell?
An amoeba-like cell that obtained nutrients by phagocytosis
What are the two key eukaryotic organelles believed to be descendants of endosymbiotic eukaryotes?
- Mitochondria
- Chloroplasts
How did chloroplasts arise?
From photosynthetic bacteria
What is a significant similarity between mitochondria and chloroplasts?
Both are double-membraned organelles
What type of DNA do mitochondria and chloroplasts contain?
Circular DNA
How do mitochondria replicate?
By simple fission, similar to bacterial cells
What evidence supports the endosymbiosis theory?
Mitochondria and chloroplasts are the same size as prokaryotic cells and divide by binary fission
What is a defining feature of prokaryotic cells?
They lack membrane-bound organelles
What are the two fundamental types of cells?
- Prokaryotic cells
- Eukaryotic cells
What component of the cell is responsible for holding its components and giving it shape?
Cytoplasm
Fill in the blank: The ______ is the outer covering separating the cell’s interior from the surrounding environment.
plasma membrane
What are the four common components of all cells?
- Plasma membrane
- Cytoplasm
- DNA
- Ribosome
What is the function of ribosomes?
Site of protein synthesis
What is the function of the nucleus
The nucleus is the control center of a cell where genetic information (DNA) is stored.
What does the Golgi apparatus do?
Forms Lysozymes, processes enzymes and proteins to be secreted from the cell.
What is the primary structure that differentiates plant cells from animal cells?
Cell wall
What is the shape of animal cells?
Round (irregular shape)
What is the shape of plant cells?
Rectangular (fixed shape)
What organelles are present in both plant and animal cells?
- Mitochondria
- Endoplasmic reticulum
- Ribosomes
- Golgi apparatus
- Cytoplasm
What is one function of the cell wall in plant cells?
Provides mechanical support and prevents osmotic bursting
What is the role of centrioles in cells?
Form spindle fibers during cell division
What are prokaryotic cells primarily composed of?
A single chromosome consisting of circular double-stranded DNA
What is the function of the capsule in bacteria?
Acts as a defense barrier against environmental factors
What is the primary composition of the bacterial cell wall?
Peptidoglycan
What type of reproduction do prokaryotic cells primarily undergo?
Asexual reproduction by binary fission
What is the timeline year associated with the first discovery of the cell?
1665
Who articulated the concept of cell theory?
Schleiden and Schwann in 1839
What are the two major groups of prokaryotic cells?
- Bacteria
- Archaea
What is the function of smooth endoplasmic reticulum?
Synthesizes, secretes, and stores carbohydrates and lipids.
Detoxification of drugs and poisons.
Store calcium for muscle contractions.
What distinguishes rough endoplasmic reticulum from smooth ER?
Rough ER has ribosomes on its surface
What is the role of the nucleolus?
Makes ribosomes
What is the primary function of mitochondria?
Site of oxidative phosphorylation and electron transport during aerobic respiration. (SITE FOR CELLULAR RESPIRATION)
What is LASM?
Site for chemical reactions in the cell.
What are the components of LASM?
A complex mixture of water and dissolved inorganic and organic solutes.
Name two examples of inorganic solutes found in LASM.
- Sodium
- Potassium
- Calcium
- Chlorides
Name two examples of organic solutes found in LASM.
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
What organelles are suspended in the cytoplasm?
- Nucleus
- Mitochondria
- Chloroplast
- Ribosome
- Endoplasmic reticulum
- Golgi bodies
What was significant about the year 1595 in cell biology?
Jansen credited with the first compound microscope.
What did Hooke describe in 1665?
He described ‘cells’ in cork.
Who discovered protozoa in 1674?
Leeuwenhoek.
What did Brown describe in 1833?
The cell nucleus in cells of the orchid.
What theory did Schleiden and Schwann propose in 1838?
Cell theory.
What did Kolliker describe in 1857?
Mitochondria.
What is the role of electrolytes in the cytoplasm?
They make it an ideal environment for chemical reactions.
What substances does the cytoplasm contain?
- Secretory substances
- Enzymes
- Hormones
What is the function of the nucleus?
Controls all physiological processes in the cell.
What are the 5 main structures of the nucleus?
- Nuclear envelope
- Nuclear pores
- Nucleoplasm
- Chromatin fibres
- Nucleolus
What is the function of nuclear pores?
Allows the passage of chemicals to and from the nucleus.
What is nucleoplasm?
Semi-fluid substance in which nucleolus, chromosomes, organic compounds, and salts are suspended.
What becomes visible when a cell is dividing?
Chromosomes.
What is the structure responsible for the synthesis of ribosomes?
Nucleolus.
What is the function of the vacuole in plant cells?
- Storage of waste and toxic substances
- Contains cell sap
What is the fluid in the vacuole called?
Cell sap.
What are ribosomes composed of?
Protein and RNA (ribonucleoprotein).
What is the role of ribosomes in the cell?
Site for protein synthesis.
What does the endomembrane system comprise?
- Endoplasmic reticulum
- Golgi apparatus
- Lysosome
What are the two types of endoplasmic reticulum?
- Rough Endoplasmic Reticulum (RER)
- Smooth Endoplasmic Reticulum (SER)
What is the main function of the RER?
Modifies protein and phospholipids for cell membrane and other organelles.
What are the main parts of a cell?
- Cell membrane
- Nucleus
- Cytoplasm
What is the difference between eukaryotes and prokaryotes?
Eukaryotes have cells containing double-membraned structures; prokaryotes lack them.
What is a similarity between prokaryotes and eukaryotes?
- Plasma membrane
- Cytoplasm
- DNA
- Ribosome
What is one limitation of the cell theory?
It does not explain the structure and functioning of viruses.
Who first discovered and named the cell?
Robert Hooke in 1665.
What does the cell theory state about living things?
All known living things are made up of cells.
What does the cell theory state about cell division?
All cells arise from pre-existing cells by division.
What component of the cell theory addresses energy flow?
Energy flow occurs within cells.
Fill in the blank: The cell theory states that cells contain hereditary information which is passed from cell to cell during _______.
cell division.
What is the function of centrioles
To form spindle fibres during cell division
What forms Lysozymes?
The golgi apparatus
What is the function of ribosomes.
Side of protein synthesis
What are the four common components in Eukaryotic and prokaryotic cells.
DNA
Ribosomes
Cytoplasm
Plasma membrane
What does the cytoskeleton consist of?
Microtubules
Filaments
Fibres
What makes ribosomes?
Nucleolus
What’s the role of pili in bacteria?
To attach the bacterial cell to specific surfaces or other cells, facilitating adhesion and colonization.
What is a tissue and give an example?
Tissue is a group of similar cells that work together to perform a specific function. Tissues are found in both plants and animals. E.g muscle tissue like cardiac muscle.
What is a tissue?
A group of cells that work together to perform a specific vital function e.g heart.
What is a system?
A system is a group of organs that work together to do a specific job. E.g digestive system.
Where are Eukaryotic cell types found?
Animals, plants, algae, fungi
What is the plasmodesta in a plant cell?
Plasmodesmata are narrow channels or bridges that connect the cytoplasm of adjacent plant cells, allowing for the exchange of molecules, ions, and even electrical signals between them.
What are the functions of Lysozymes?
Site for intracellular digestion.
Contains hydrolytic enzymes to digest proteins.
What makes Lysosomal enzymes and membranes?
Rough endoplasmic reticulum and transferred to golgi for processing.
Why are Lysosomal membranes highly glycosylated?
To protect them from Lysosomal proteases.
What is autophagy
Process in which cells recycle their own organic material.
What is the folded inner membrane of the mitochondria called?
Cristae. It is folded to increase the surface area
Mitochondria produces energy for cell. What is it’s other name?
Power house of a cell
The cytoskeleton is a network of fibres extending throughout the cytoplasm. What is it’s function?
Mechanical support.
Locomotion
Establish cell shape
Intracellular transport of organelles
3 Types of fibre in cytoskeleton.
Microtubules: determine position of membrane enclosed organelles
Microfilaments: determine shape of cell
Intermediate filament: provide mechanical strength and resistance to stress.
What are cilia and flagella constructed from?
Microtubules
Describe the movement in cilia and flagella
Cilia works like ores, direction perpendicular to the cilium’s axis.
Flagellum has undulating motion in the same direction as the axis
The cell wall of a prokaryotic cell does not contain cellulose or chitin. What does it contain?
Carbohydrates and amino acids(Peptidoglycan)
Explain growth and reproduction in Prokaryots.
They reproduce asexually by binary fission but some do it sexually in a process called conjunction(assisted by pili) which involves exchange of DNA between adjacent cells.
They grow rapidly and have short life span but form colonies quickly.
Use of Prokaryots( like bacteria and archaea in our lives)
Produce food stuffs, chemicals and drugs
Explain growth and reproduction in Eukaryots
Eukaryotes (Plants, Animals, Fungi, Protists)
1. Mitosis and Meiosis: Eukaryotes grow and reproduce through mitosis (cell division) and meiosis (sexual reproduction).
2. Complex Cell Division: Eukaryotes undergo complex cell division processes, including mitosis and meiosis, which involve the replication and separation of chromosomes.
3. Slower Reproduction: Eukaryotes generally reproduce more slowly than prokaryotes, with longer generation times.
What is mRNA, tRNA and rRNA?
Types of RNA
mRNA (Messenger RNA)
Carries genetic information from DNA to the ribosome for protein synthesis.
tRNA (Transfer RNA)
Brings amino acids to the ribosome during protein synthesis.
rRNA (Ribosomal RNA)
Makes up a large part of the ribosome, which is responsible for building proteins.
What does RNA mean?
RNA stands for Ribonucleic Acid.
