Cells Flashcards
What is a cell
A cell is the basic unit of structure of all living things which make up tissue. Organisms can either be described as Prokaryotes(containing 1 cell) or Eukaryotes(containing many cells)
Describe Prokaryotes and Eukaryotes
Prokaryotes are cells that have no nucleus or membrane-bound organelles while Eukaryotes have a nucleus and do contain membrane-bound organelles. Examples of Prokaryotes are bacteria and Eukaryotes are animal cells, plant cells, and fungi.
What is the endosymbiont theory
Mitochondria and chloroplast originated from prokaryotic cells that were engulfed and adopted by an ancient host cell. The bacterial ancestor of mitochondria and chloroplast are endosymbionts. An endosymbiont is an organism that lives within a dissimilar organism. Endosymbionts had the ability to trap or convert energy from their surroundings, this ability was necessary for Heterotrophic cells. Heterotrophic cells couldn’t create carbon-containing compounds and received that from plants and animals. The heterotroph together with the endosymbiont had the advantage of respiration and photosynthesis to make their own food. These heterotrophic cells were the ancestors of eukaryotes. Mitochondria and Chloroplast cannot live independently outside their host cell because they cannot meet their own needs.
What are 5 pieces of evidence of the endosymbiont theory
Chloroplasts are the same size as prokaryotic cells divide by binary fission and are like bacteria
The mitochondria are the same size as prokaryotic cells and divide by binary fission
Mitochondria and chloroplast have their own DNA that is circular and not linear
Mitochondria and chloroplast have their own ribosomes that have 30s and 50s subunits not 40s and 60s
Both have nuclear membranes surrounding them
Describe mitochondria
Mitochondria is a membrane-bound organelle found in the cytoplasm of eukaryotic cells. It is the powerhouse of the cell; it is responsible for the cellular respiration and production of most ATP in the cell.Site of aerobic respiration and contain a small fraction of the cell’s genes.
Describe Chloroplast
Chloroplasts are organelles that conduct photosynthesis where the photosynthetic pigment chlorophyll captures the energy from sunlight, converts It, and stores it in the energy storage molecules ATP and NADPH while freeing oxygen from water in plant and algae.
Describe Nucleus and Nuclear Envelope
It contains most of the cell’s genetic material organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cells nuclear genome.
It contains a nuclear envelope that is impermeable to most molecules.It has nuclear pores which create a channel that allows free movement of small molecules and ions.
Describe Chromosomes
Chromosomes are multiple linear DNA molecules organized into structures. During most of the cell cycle they are organized in a DNA rotein complex known as chromatin which form the well defined chromosome during cell division.
Describe Golgi Apparatus
The Golgi apparatus is an organelle found in eukaryotic cells and is part of the endomembrane system in the cytoplasm which packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination
Describe Endoplasmic Reticulum
It is a continuous membrane system that forms a series of flattened sacs within the cytoplask=m of eukaryotic cells and serves multiple functions being important in the synthesis folding modification and transport of proteins.
What are the epidermis, endodermis, pericycle and Vascular tissue of a Ranunculus root
Epidermis- Made up of epidermal cells that form a covering on the outside of the root. Some cells have projections that make up root hairs.
Endodermis- Layer of cells surrounding the stele that contain specially waterproofed by a deposit known as the Casparian strip
Pericycle- Layer of cells within the stele that surround vascular tissue
Vascular Tissue(makes up stele)- involved in the transport of materials through the plant
What is the Cortex of a Ranunculus Root
The cortex is made up of parenchyma tissue, the cells of which have thin cell walls to facilitate the flow of water from the edge of the root to the center.Also, starch storage and structural support when turgid.
What are the xylem and phloem in the Ranunculus Root
Xylem Tissue- made up of dead empty cells with lignified cells walls and no end walls called vessel elements. These join end to end to form continuous tubes through which water flows in an unbroken column
Phloem Tissue- made up of phloem sieve elements which are living cells with cellulose cell walls with perforated end walls to allow sucrose solutions to move through. They have no nucleus little cytoplasm and few organelles and are connected to the companion cells via the plasmodesmata.
What is the role of phospholipids in the cellular membrane
Forms the fundamental basis of the membrane to which all other component ts are embedded since it forms the bilayer
Affects the fluidity and permeability of the membrane
Due to continuous bilayer, it serves as a barrier to hydrophilic substances such as ions and molecules that carry a charge
Allow lipid-soluble substances to enter and leave the cell
What is the role of cholesterol in the cellular membrane
Adds to the fluidity of the membrane buffer against becoming too stiff in low temperatures or too fluid when temperatures are high
Prevents the lateral movement of phospholipids
