cell biology Flashcards
what type of cell is a prokaryote?
bacteria
what is cell differentiation?
process by which a cell changes to become specialised
Function of the cell wall?
The cell wall is to give the cell strength and structure, and to filter molecules that pass in and out of the cell.
Function of the cell membrane?
It only lets certain molecules enter and exit (regulates the movement of substances in and out of cells.
Function of vacuole?
Is the storage structure in a cell. It can hold food for later use or waste for removal.
Function of chloroplast?
It conducts photosynthesis, or make its own food and energy. Is an organelle. Used to make chemical reactions take place.
Function of cytoplasm?
The fluid inside a cell but outside the cell’s nucleus. Most chemical reactions in a cell take place in the cytoplasm.
Function of nucleus?
Controls other cell functions and contains genetic material.
Function of ribosomes?
Responsible for synthesising proteins - site at which synthesis occurs.
Function of mitochondria?
Responsible for energy release in the cell by respiration.
What’s an organelle?
Each of the structures inside a cell is called and organelle.
What’s a eukaryotic?
cells with nucleus
Muscle cells contain…
Contain special proteins that can slide past each other. When muscles contract they move.
features of Red blood cells?
-adaptations etc
Large surface area.
Carry oxygen around the body.
Contains haemoglobin which binds to oxygen.
No nucleus( so more haemoglobin can be carried) because cell has a single function.
White blood cells?
Lots of ribosomes.
Destroy & engulf pathogens.
Make antibodies.
Neurone?
To carry nerve impulses around your body.
These are extremely elaborated cells
they have many branches at both ends to connect to other nerve cells.
The long axon is covered in insulating myelin for faster conduction.
Ciliated cells?
Designed to stop lung damage.
Cilia sweep mucus with trapped dust and bacteria back up the throat to be swallowed.
They live in the air passages to the lungs.
They have tiny hair like structures.
difference in plant and animal cells abilities to differentiate
most animals lose the ability after specialisation, but most plants don’t. in mature animal cells they are used for repairing such as blood cells or skin
desc Sperm cells?
Carries genetic material to produce a new organism.
Flattened head, contains nucleus and acrosome.
Elongated flagellum (tail)
Many mitochondria in middle section.
Diffusion?
Diffusion is the movement of particles( in a gas or solute) from high concentration of the particles to low concentration.
Structures involved in diffusion usually have large surface area.
It’s is a passive process- it occurs without the need for any outside influence.
Osmosis?
Osmosis is the movement of water molecules from a high concentration of water to a low concentration of water. This happens across a semi-permeable membrane and is a passive process.
Active transport?
Movement of particles.
From low to high concentration.
Up a concentration gradient.
This requires an input of energy.
provided by the mitochondria in a cell.
Root hair cell?
The root hair cell has a large surface area to provide contact with soil water. It has thin walls so as not to restrict the movement of water.
Xylem cell?
There are no top and bottom walls between xylem vessels, so there is a continuous column of water running through them. Their walls become thickened and woody. They therefore support the plant. Transports water and minerals.
Phloem?
Dissolved sugars and amino acids can be transported both up and down the stem. Companion cells, adjacent to the sieve tubes provide energy required to transport substances in the phloem.
Nerve cells?
-carry electrical signals from one part of the body to another.
-long (to cover more distance)
-have branched connections at their ends to connect to other nerve cells and form a network around the body.
Organelles in a leaf structure?
Waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, guards cells and stoma.
What does flaccid mean?
Lacking turgor. Lacking in stiffness or strength. Soft and floppy.
What does turgid mean?
Enlarged and swollen with water.
Function of palisade mesophyll?
Carries out photosynthesis
Function of spongy mesophyll?
Allow gases to circulate for the exchange of gases between the leaf and the environment, carry out some photosynthesis
Function of guard cells?
Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen
Function of sieve cells?
Transport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed
Function of companion cells?
Provide the energy required for transporting substances in sieve tubes
Function of xylem vessels?
Transport water and dissolved minerals from the roots, up the plant
Function of waxy cuticle?
The cuticle reduces the rate of water loss from the leaf surface
Platelets?
Involved in blood clotting
Plasma?
transporting CO2, digested food molecules, urea and hormones; distributing heat.
what is mitosis?
a cell reproducing by splitting into two identical offspring
process of mitosis:
-cell begins to divide
-DNA replicates to form two copies of each chromosome
-nuclear membrane breaks down, chromos line up across centre of cell
-one set of chromo pulled to each end of cell and nucleus divides
-cyto and nucleus divide to form two identical cells
binary fission process:
-plasmids and circular DNA replicate
-cell gets bigger and the circular DNA strands move to opp ends of cell
-cyto begins to divide, new cell wall begins to form
-cyto divides, d cells formed, each have one copy of circular DNA, but can have a variable number of plasmids.
what are stem cells?
-cells that divide by mitosis to produce more cells
-they differentiate into diff types of specialised cells
two different types of stem cells?
-embryonic stem cells (can differentiate into any cell)
-adult stem cell (found in bone marrow)
can only make blood cells
purpose of stem cells:
to replace faulty cells
cause of type 1 diabetes:
pancreas damaged and doesn’t prod insulin
why do plants need mg ions:
to prod chlorophyll
why do plants need nitrates:
to prod proteins
what is cytokinesis
the cell membrane pinching in and dividing into two daughter cells
Rare species of plants can be cloned so they don’t go extinct. To do this, stem cells are taken from the __________ of the plant. What one word completes the sentence?
Meristems, found in root and shoot tips, are regions of unspecialised cells in plants that are capable of cell division. They can develop into any type of specialised cell.
The …….. is a large sac in the middle of the cell that contains a watery solution of sugars and salts (cell sap). It helps maintain the ……. and ……… of the cell.
vacuole
structure, shape
List 4 factors that affect the rate of diffusion.
Concentration gradient
Temperature
Surface area
Distance to diffuse across (if diffusing across a membrane)
What is the role of the mitochondria?
Mitochondria are the site of aerobic respiration, so they release energy for the cell.
State and explain three features of villi that make them good exchange surfaces.
Feature 1 - There are lots of villi, and each villi has microvilli, giving a large total surface area
Explanation 1 - Lots of molecules can diffuse across at the same time
Feature 2 - Surfaces are very thin (only 1 villi cell and 1 capillary cell thick)
Explanation 2 - Substances only have to diffuse a short distance
Feature 3 - Surfaces are permeable
Explanation 3 - Glucose, amino acids, vitamins etc are able to pass through the villi cells
Feature 4 - Good blood supply (good supply of ‘internal medium’)
Explanation 4 - Maintains a strong concentration gradient as blood is constantly replaced
Describe what happens during each stage of the cell cycle.
(stage 1)
-DNA / chromosomes replicate / duplicate
-mitochondria / ribosomes /sub-cellular structures replicate
(stage 2)
one set of chromosomes is pulled / moved to each end of the cell
(stage 3)
the cytoplasm and cell membrane divides (to form two cells)
function of a nucleus
controls activities of a cell
Why is bile not being able to reach the small intestine a problem?
no / less bile reaches the small intestine
less / no emulsification of fat
smaller surface area for lipase to break down fat
pH of small intestine is not neutralised / alkaline
lipase is not at its optimumpH to break down fat
