cells Flashcards
What is a nuclear envelope?
The nuclear envelope is a double membrane surrounding the nucleus
What is the function of the holes in the nucleus and what is it called
Materials can move in and out of the nucleus via tiny holes in the nuclear envelope, called nuclear pores
remindier it brakes down during prophase of mitosis
what and where are the ribosomes assembled
Within the nucleus, ribosomes are assembled by the nucleolus.
what are vascles
Small fluid-filled sacs transport substances around inside a cell
what are the small fluid-filled sacs transport substances around inside a cell
vascles
What are ribosomes made up of?
Ribosomes are made up of RNA and proteins.
What are the functions of the Golgi apparatus?
The Golgi stores and modifies proteins and lipids.
It then packages these substances into vesicles for transportation.
Some of the proteins packaged are enzymes. These enzymes are used to form lysosomes.
What is a lysosome?
A lysosome is a membrane-bound organelle that releases digestive enzymes.
What is the function of the mitochondria?
Mitochondria are the sites of aerobic respiration and production of ATP.
What does the inner membrane in of the mitochondria form
Citrine
What is the rough endoplasmic reticulum?
The rough endoplasmic reticulum (RER) is a system of folded membrainesthat has ribosomeson its outer surface.
The rough endoplasmic reticulum is where ribosomesare processed and packaged into vescles.
How does the structure of the rough endoplasmic reticulum help enable the synthesis of proteins?
The rough endoplasmic reticulum has ribosomes and a large surface area.
What is the smooth endoplasmic reticulum?
The smooth endoplasmic reticulum is a system of membranes with no ribosomes on the outer surface.
The smooth endoplasmic reticulum is where carbohydrates and lipids are secreted and packaged into vesicles.
What is the function of the plant cell wall?
The plant cell wall provides rigidity to the cell.
The cell wall stops the cell from bursting as water enters it by osmosis, and this enables the cell to become turgid.
What is the function of the vacuole in a plant cell?
The vacuole supports the plant by making cells turgid.
It also stores sugars and amino acids, which can act as a temporary food store.
What are plant cell walls mainly composed of?
Plant and algal cell walls are mainly composed of the polymer cellulose.
Fungal cell walls are mainly composed of which polymer
chitin
What are thylakoids?
Thylakoids are flattened sacs in the chloroplast, containing the pigment chlorophyll.
What are grana?
Grana are stacks of thylakoids found in the stroma of a chloroplast
Starch and glycogen are coiled. Why does this make them good storage molecules?
It makes the molecules compact.
What are prokaryotic cells?
Prokaryotic cells are single-celled organisms that lack membrane-bound organelles.
In prokaryotic cells, the cell wall is made of….
murein
A bacterium has a protective outer layer called a…
capsule
a capsule protects a prokaryote from…
excessive water loss.
the host immune system.
Some prokaryotic cells have small loops of DNA in their cytoplasm.
These are called…
plasmids
Viruses also need a host cell in order to replicate.
As a result, we say that viruses are…
parasitic particles.
acellular.
Some viruses have a protective outer envelope made of…
phospholipids
Scanning electron microscopes provide …
a 3D image of the outer surface of a sample.
transmission electron microscopes provide….
2D image of the sample’s internal structure.
Historically, when using microscopes to look at cells, scientists struggled to distinguish cell organelles from other objects not part of the sample.
These objects are called
Artefacts
Sequence the steps of cell fractionation:
Step 1: Homogenisation
The cells in the tissue sample are broken up.
Step 2: Filtration
Large cell debris and unbroken cells are removed.
Step 3: Ultracentrifugation
The cell organelles are separated.
During the first step of cell fractionation, homogenisation, the tissue sample is placed in….
in an ice-cold, buffered and isotonic solution.
Why is the solution buffered in the homologation phase of ultra centrifuging
To prevent enzymes and other proteins from denaturing
Why is the solution isotonic in the homologation phase of ultra-centrifuging
To prevent osmosis, which could cause lysis (bursting)
After the first two steps in cell fractionation, homogenisation and filtration, we end up with a filtered solution.
What does this solution contain?
Cell organelles
what is formed ath the bottom of the tube within a centrifuge
a pellet
within a centrifuge the remaining liquid in the tube is called the
supernatant.
