cells Flashcards
what is cell theory?
principle that all living organisms are made up of cells and the materials produced by cells.
what is the cell membrane?
membrane that forms the external boundary of a cell; plasma membrane.
surrounds the cell and separates the cell from neighbouring cells and separates its contents from the external environment neighbouring outside of the cell
thin
made of a double layer of lipid molecules and associated proteins
determines which substances gets in and out of cells.
what is the cytoplasm?
the contents of the cell excluding the nucleus. protoplasm.
thick fluid filled inside of the cell and the suspended structures that it contains.
what is the cytosol?
the liquid part of the cytoplasm of the cell. 75-90% water.
what are the organelle?
structures within the cytoplasm of the cell, each with specific functions.
what is the nucleus?
largest organelle contains DNA oval or spherical in shpae separate through nuclear membrane has pores has nucleolus which has RNA DNA and nucleolus are suspended jelly like nucleoplasm
what are nuclear pores?
gaps in a the nuclear membrane
What is DNA
deoxyribosenucleaic acid .
molecule that determines the type of protein a cell can make
contains genetic info
inherited
when cell not dividing, DNA is in form of long threads
when cell is dividing, threads thicken and coil to form chromosomes.
what are chromosomes?
one of the 46 rod like structures that appear int eh nucleus of a human cell at the start of cell division
what is the nucleolus?
structure within the cell’s nucleus, involved in protein synthesis.
made of RNA
what are ribosomes?
very small and special; may be free in the cytoplasm, but not are attached to membranes.
amino acids are joined together at the ribosomes to make protein
what is the endoplasmic reticulum?
Paris or parallel membranes extending though the cytoplasm and connecting the cell membrane with the nuclear membrane. provides a surface in which chemical reactions can occur. the channels between the paired membranes are used for storage or transport of materials.
most er have ribosomes which makes them rough/granular
er that have no ribosomes are smooth agranular
what is the Golgi body/apparatus?
structure in the cytoplasm of the cell consisting of a stack of flattened membranous (bags) channels.
they modify proteins and package them in vesicles for secretion.
small bubbles of liquid containing proteins are formed, called vesicles. they are pinched off from the edges of the membrane
proteins produced at the ribosomes pass through the channels of the endoplasmic reticulum to the Golgi body for secretion though the vesicels
what are vesicles?
a small membrane bound cavity in the cytoplasm of the cell, smaller than a vacuole.
what are lysosomes?
a small sphere formed form the Golgi body; contains digestive enzymes to break down proteins, lipids, nucleic acids and carbs.
they break down materials, large molecules that are taken into the cell and also the worn out organelles.
when particles or liquids are taken into the cell, they form vesicles int he cytoplasm. lysosomes can join with the vesicles and the digestive enzymes they contain to break down the materials inside the vesicles.
