Cell: The Unit Of Life Flashcards
What is a cell?
fundamental structural and functional unit of all living being
Who invited the single microscope (single biconvex lens)? What as the max. magnifying?
Antony van Leeuwenhoek, 200x
Who invented the compound microscope? (using 2 biconvex lens)? What was the max. magnifying?
Robert Hooke, 200,000x
What is the cell theory? Who made it?
Mathias Schleiden, Theodor Schwann, Rudolf Virchow
Cells are structural unit, functional unit, arise from existing cells, life starts as single cell.
Explain the no. of cells with examples.
Single-celled: Bacteria, Yeast, Amoeba
Few-celled: Spirogyra, Volvox
Multi-celled: Humans, Trees
What is the smallest, longest and largest cell?
smallest: bacteria (0.3-5.0 micrometer)
longest: nerve cells
largest: ostrich eggs
Why are cells so small?
1) different areas of a cell can communicate rapidly.
2) cells have larger surface area than volume for better diffusion.
What are functions of various cell shapes?
1) WBCs are amoeboid to squeeze through capillary walls
2) Nerve cells are long to conduct impulses throughout the body.
3) Muscle cells are long and contractile for movement.
4) Guard cells of stomata are bean shaped to open and close.
What parts does a generalised cell contain?
Cell membrane, nucleus and cytoplasm.
What are cell organelles?
living parts of the cell.
What is the function of the cell membrane? What is its permeability?
It has pores so that substances can enter or leave the cell. It is selectively permeable.
What is the cell membrane made of? Is it living or dead?
Lipoproteins. Living.
What is the function and location of the cell wall?
It gives shape and rigidity to the cell without interference with cell functioning. It surrounds the cell membrane.
What is the cell wall’s permeability? Which cells is it present in?
It is freely permeable. It is present in plant cells only.
What is the cell wall made of? Is it living or dead?
It is made of cellulose. It is dead.
What is the location of cytoplasm? What are its features?
It occupies most of the cell within the membrane. It is a semi-liquid substance. It looks colourless, translucent and watery.
What occours in the cytoplasm? What is its constant state?
Chemical reaction take place. It is in a constant state of motion.
What are the characteristics of endoplasmic reticulum?
irregular network of double membraned tubules
continuous structure with plasma membrane on one end and nuclear membrane on the other
smooth or rough(with ribosomes)
What is the function of endoplasmic reticulum?
supportive framework of cell, synthesis and transport of proteins and fats
What are the characteristics of mitochondria?
double walled, inner wall is folded into cristae, have own DNA containing several genes, contain ribosomes
What are the functions of mitochondria?
seat of cellular aerobic respiration and stores energy, releases energy in form of ATP, synthesis of respiratory enzymes
What are the characteristics of Golgi apparatus/dictyosomes?
stacks of flattened membrane sacks, consists of cisternae, vacuoles and vesicles
What are the functions of golgi apparatus/dictyosomes
synthesis and secretion of hormones, formation of acrosome of sperm in animals
What are the characteristics of ribosomes?
small granules in cytoplasm or on ER, single walled, dense, spherical bodied, made of RNA
What are the functions of ribosomes?
protien synthesis
What are the characteristics of lysosomes?
membranous sacs budded off from golgi bodies, contain 40 enzymes
What are the functions of lysosomes?
intracellular digestion, destruction of foreign substances, self destruction, digestion of cartilage during bone formation
What are the characteristics of centrosomes?
region surrounding centrioles, near nucleus, form asters during cell division, surrounded by radiating microtubules, contains one or two centrioles, only in animal cell
What are the functions of centrosome?
initiate and regulate cell division, form spindle fibres with help of asters
What are the characteristics of plastids?
double membraned, contain protienaceous matrix, contain DNA , only in plants
What are the functions of plastids?
chromoplast plays imparts color to flowers for pollination (carotene and xanthophyll)
chloroplasts traps solar energy for photosynthesis
leukoplasts stores starch
What are the characteristics of nuclei?
largest organelle, spherical and dense, allows substance to enter or leave, contains network of thread like structures called DNA
What are the functions of nucleus?
regulates cell function, contain chromosomes, if removed cell dies
What are the characteristics of nucleolus?
one or more round shaped structures inside nucleus
What are the functions of nucleolus?
produces ribosomes, forms and stores RNA, dictates ribosomes to synthesise protien
What are the characteristics of chromatin fibres?
network in resting stage on nucleus condenses into chromosomes, made of DNA threads
What are the functions of chromatin fibres?
carry genes to offspring’s from parents
What are the characteristics of vacuoles?
have clear spaces with water in solution, plants have large but less, animals have small but many, covered by tonoplast
What are the functions of plastids
store water, food, waste product, etc, give turgidity to plant cells by pressing against cell wall, contain pigment like anthocyanins
What are the characteristics of granules?
small particles, crystals or droplets
What are the functions of granules?
store starch in plant cells, glycogen in animal cells and fat containing globules serving as food for cell
