cells Flashcards
(24 cards)
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.
what is the mitochondria?
a structure in the cytoplasm of a cell in which the aerobic stage of respiration occurs. (mitochondrion).
it is spherical /elongated structures spread throughout the cytoplasm.
has a double membrane - outer is smooth the inner is folded in centre of the mitochondrion - increase of surface area in which these chemical reactions can take place (cellular respiration, occurring in mitochondria)
releases energy for the cell through respiration
cell
powerhouse of the cell as it makes energy avail el for the cell.
what is cellular respiration?
chemical reaction that makes energy available for the cell; tissue respiration, internal respiration.
C6H1206 +6O2 –> 6CO2 +6H20+ATP
what are centrioles?
pair of cylindrical structures in the nucleus, involved in the reproduction of the cell.
what is cilia?
hair-like processes projecting form a cell, they beat rhythmically to move to the whole cell or to move material across the cell surface (cilium) short and many. occurs in the cell lining of the windpipe, moving mucous and trapped particles towards the throat.
what is a flagella?
a long hair on projection from sperm, having the function of moving the cell (sperm to egg).
long and few.
what is the cytoskeleton?
an internal scaffolding of protein fibres within the cytoplasm of a cell.
framework of protein fibres that gives the cell its shape and assists cell movement.
consists of microtubules and microfilaments.
what are microtubules?
fine, hollow rods tubes that help to maintain the shape of the cell and hold the organelles in place or move them around the cell.
what are microfilaments?
protein fibres that move materials around the cytoplasm or move the whole cell.
what are inclusions?
chemical substances that are not part of the cell stricter but are found in the cytoplasm of the cell
eg. haemoglobin in red blood cell is an inclusion they contain no nucleus to allow more room for haemoglobin
skin cells, hair cells and iris have melanin - inclusion.
