1.2 cell structure and organisation Flashcards
what is a eukaryotic cell?
a cell that contains membrane-bound organelles.
what is a prokaryotic cell?
a cell that does not contain any membrane-bound organelles.
what is the nuclear membrane?
a double membrane surrounding the nucleus.
what is the job of the nuclear pores?
to allow the passage of some molecules, such as mRNA, between the nucleus and cytoplasm.
what is the job of the nucleolus?
synthesises components of ribosomes and makes rRNA.
what is the nucleoplasm?
a granular material containing chromatin.
what is chromatin made up of?
DNA molecules bound with proteins called histones.
what is the job of the nucleus?
it contains DNA which codes for protein synthesis.
what is the cristae?
the inner membrane of the mitochondria that increases its surface area.
what is the matrix?
similar to the cytoplasm, it contains enzymes involved in the Krebs cycle.
why do the mitochondria and chloroplasts have 70s ribosomes and small circles of DNA?
so the mitochondria can self replicate and synthesise their own proteins.
what is the job of the mitochondria?
ATP synthesis by aerobic respiration.
what is the stroma?
the fluid found between the double membrane containing ribosomes, circular DNA, and lipids.
what is a thylakoid?
a flattened sac within the stroma containing chlorophyll.
what is a benefit of the granum?
the stack of thylakoids means a bigger surface area for trapping light energy.
what is the job of the chloroplast?
it traps light energy, which is used to synthesis carbohydrates and also in photosynthesis.
what is the endoplasmic reticulum?
a membrane system found throughout the cytoplasm of eukaryotic cells.
what is on the surface of the rough ER?
it has ribosomes on its surface.
what is the job of the rough ER?
manufactures and transports proteins.
what does the smooth ER lack?
it has no ribosomes on its surface.
what is the job of the smooth ER?
it manufactures and transports lipids.
where is the ER found on the electron microgram?
next to the nucleus.
what is the job of the ER?
it is found in large amounts in cells that make enzymes that may be secreted out of the cell?
what is the golgi body?
it consists of a number of flattened sacs in which proteins and other molecules are modified.
what are the jobs of the golgi body?
produces secretory enzymes; secreting carbohydrates; producing glycoprotein; transporting and storing lipids; forming lysosomes containing digestive enzymes.
where are ribosomes found?
free within the cytoplasm or attached to the rough endoplasmic reticulum.
what are ribosomal subunits?
a large and a small subunit made from ribosomal RNA and protein.
where are the subunits manufactured?
the nucleolus.
what size ribosomes do prokaryotic cells have?
70s (smaller)
what size ribosomes do eukaryotic cells have?
80s (bigger)
what is the job of the ribosomes?
they are the sites of protein synthesis. they synthesise proteins at their primary structure.
what kind of membrane surrounds the lysosomes?
a single membrane.
where are lysosomes formed?
in the golgi body.
what is the job of the lysosomes?
they contain digestive enzymes that break down cellular waste and debris.
