Unit 1 - Cell biology Flashcards
what do unicellular and multicellular mean?
unicellular - single celled
multicellular - multiple cells
what is the function of the cell membrane and what cell types is it found in?
it controls the entry and exit of materials into and out of the cell
found in all cells
what is the function of the cell wall and what cells are they found in?
they are a rigid structure around a cell, giving shape and support. they are made of cellulose and are freely permeable.
found in fungi, bacteria and plant cells.
what is the function of the nucleus and what cells are they found in?
controls all cell activities and contains genetic material
found in animal, plant, fungi
what is the function of the chloroplast and what cells are they found in?
site of photosynthesis. contains chlorophyll to absorb light energy.
plant cells only
what is the function of the mitochondrion and what cells are they found in?
site of aerobic respiration. where the cell produces most of its energy in the form ATP
found in animal, plant, fungi
what is the function of the vacuole and what cells are they found in?
they contains cell sap
found in plant, and fungi cells
what is the function of the ribosome and what cells are they found in?
they are the site of protein synthesis
they are found in all cells
what is the function of the plasmid and what cells are they found in?
they are a circular structure containing DNA
found only in bacteria
what is the function of the cytoplasm and what cells are they found in?
they are the site of chemical reactions
they are found in all cells
name all the cell structures in an animal cell?
nucleus, cell membrane, mitochondria, cytoplasm, ribosome,
name all the cell structures in a plant cell?
vacuole chloroplasts cell wall cell membrane mitochondria ribosomes nucleus cytoplasm
name all the cell structures in a fungal cell?
nucleus mitochondria cell membrane cell wall vacuole ribosomes cytoplasm
name all the cell structures in a bacterial cell?
ribosomes plasmid DNA capsule cell wall cell membrane cytoplasm
describe cell membranes?
all cells have a cell membrane which allows molecules to enter and exit and the cell
it is selectively permeable, allowing only small, soluble molecules such as water, and oxygen to pass through.
what are the two main components of the cell membrane?
phospholipids and proteins
why does there have to be a double layer of lipids?
so the phospholipids don’t get there tails wet.
when does passive transport occur?
it occurs when molecules or a substance move down a concentration gradient, and it doesn’t require energy
what is diffusion?
diffusion is the passive process where molecules move from an area of high concentration to an area of low concentration, down a concentration gradient until they are spread evenly
what is a concentration gradient?
a concentration gradient is the difference in concentration between two substances
why is diffusion important?
diffusion is important to cells as it allows an uptake of raw materials and exit of waste materials
what molecules can move through passive transport?
in = oxygen, amino acids, glucose out = Carbon dioxide, water and urea
what is osmosis?
the movement of water molecules from an area of high water concentration to an area of low water concentration through a selectively permeable membrane. it does not require energy and occurs down a concentration gradient.
what conditions do you need for an animal cell to shrink?
the water concentration outside the cell would need to be lower so the water would diffuse outside the cell causing it to shrink
what conditions do you need for an animal cell to burst?
the water concentration outside the cell would need to be higher so the water would diffuse into the cell causing it to burst
what conditions do you need for a plant cell to become turgid?
the water concentration outside the cell would need to be higher so the water would diffuse into the cell causing it to become turgid
what conditions do you need for a plant cell to become plasmolyzed?
the water concentration inside the cell would need to be higher so the water would diffuse out of the cell causing it to become plasmolyzed.
What is active transport?
active transport occurs when molecules and ions move from a lower concentration to a higher concentration. this occurs against the concentration gradient and therefore requires energy
proteins in the membrane help pump these ions across the membrane during active transport
what does the nucleus contain?
the nucleus contains genetic information (DNA) organized into chromosomes.
Why do we need to produce new cells?
to repair damaged cells, to replace dead cells and to grow new cells.
What is mitosis?
Mitosis is the division of the cell nucleus, it ensures that the cells have the same chromosome complement to the parent cell
It produces two identical daughter cells to the parent cell. there is no loss in genetic information.
What are the stages of mitosis?
Stage 1:
chromosomes are not visible
chromosomes are replicating to prepare for division
Stage 2:
Chromosomes coil up and become visible
chromosomes made up of two chromatids, that are joined in the middle by a centromere
Stage 3:
Chromosomes line up at the equator of the cell
Chromosomes attached to spindle fibers by the centromere
Stage 4:
Spindle fibers contract
Chromosomes are pulled apart to opposite poles of the cell
Stage 5:
Cytoplasm starts to split in two
Nuclear membrane reforms
Stage 6:
two new cells are formed
they are identical to the original cell
What are chromosomes made of?
Chromosomes are made of genes, which are made of DNA
What is DNA?
DNA looks like a double-stranded helix that carries the genetic code for making protiens
Name the 4 bases and their pairs?
Adenine, guanine, cytosine, thymine.
A — T
C — G
What does the order of bases mean?
the order of bases determines the order that the amino acids will join up together to make a protein molecule
What is a gene?
A length of DNA that codes for a specific sequence of amino acids to make a protein is called a gene
What is protein synthesis?
Protein synthesis is the building of amino acids into protein chains. It takes place on the ribosomes in the cytoplasm.
During this, an mRNA molecule is sent out of the nucleus to the ribosome with a copy of the genetic code.
The nuclear membrane allows the mRNA through as it is porous.
What does mRNA do?
mRNA carries a complementary copy of the genetic code for a single protein which must be taken to the ribosomes from the nucleus.
why do different proteins arise?
different proteins arise due to different combos of the 20 amino acids.
Does the shape of the protein molecule affect its function?
Yes
Name the 5 types of proteins and a short definition.
Structural: involved in the makeup of cell structures or are present in proteins in the hair, nails and muscles
Hormonal: Acts as chemical messengers between cells, they travel in body fluid such as blood
Antibodies: Proteins involved in the bodies defence system
Receptors: Present on the sell membrane and recognise specific substances
Enzymes: Speed up chemical reactions whilst remaining unchanged
What are enzymes?
They are biological catalysts made by all living cells
What is the substrate?
The substrate is the substance upon which the enzyme acts on. Enzymes bind to substrate molecules on the active site
Why are enzymes specific?
They are specific because of the shape of the active site (one enzyme can only react with one specific substrate)
When will an enzyme be most active?
in its optimum conditions
What is required for an enzyme to become denatured?
The pH or temperature is wrong. This changes the shape of the enzyme meaning it is denatured.
What is genetic engineering?
Genetic engineering is when genetic info. is transferred from one cell to another. This often involves transferring the information from one species to another. It may involve bacteria, but not always.
Can genetic engineering help other species make a protein they normally cannot produce?
Yes. Pieces of a chromosome can be transferred from a donor species to make a protein that is normally made by another species
What are the stages of genetic engineering?
Stage 1:
The section of DNA containing the required gene is located on the chromosome
Stage 2:
The gene is then cut out of the chromosome using specialised enzymes
Stage 3:
A plasmid is cut out of a bacteria cell and cut open using enzymes
Stage 4:
The gene is then inserted into the plasmid
Stage 5:
The plasmid is inserted into a host cell, producing a GM organism
Stage 6:
Host cell multiplies/reproduces
definition of photosynthesis?
Photosynthesis is the chemical process by which green plants make carbohydrate.
Where does photosynthesis take place?
It takes place in the chloroplasts, the chlorophyll in the chloroplast traps the light energy
What is the word equation for photosynthesis?
light energy
carbon dioxide + water —————–> glucose + oxygen
chlorophyll
What are the names of the two stages of photosynthesis?
1) photolysis/light dependent reaction
2) Carbon fixation
Describe what happens during photolysis?
during photolysis light energy from the sun is used to split water into its two components, oxygen and hydrogen.
The light energy is trapped by the chlorophyll and converted into chemical energy which is used to generate ATP.
Oxygen diffuses from the cell and hydrogen joins with a hydrogen acceptor and is carries to the second stage
Describe what happens during carbon fixation?
In carbon fixation the hydrogen from photolysis combines with carbon dioxide using ATP from photolysis. This produces glucose.
Carbon fixation is a series of enzyme controlled reactions
What are the three fates of glucose?
The three fates of glucose are:
Used in respiration
converted into storage starch/fat/protein
converted into structural cellulose for new cell walls
What is a limiting factor?
A limiting factor is a variable that, when in short supply can limit the rate of a chemical reaction such as photosynthesis
What are the limiting factors of photosynthesis?
The limiting factors of photosynthesis are:
-light intensity
-temperature
-Carbon dioxide concentration
If any of these 3 factors are in short supply, photosynthesis will not occur and cell growth will stop.
What is the definition of respiration?
Respiration is a series of enzyme controlled reactions going on in all cells by which chemical energy is released from glucose.
How is ATP made?
from the breakdown of glucose
What cellular processed can ATP be broken down for?
- Cell division
- active transport
- protein synthesis
What is aerobic respiration?
CO2, energy and water are produced during aerobic respiration. Glucose and oxygen are needed for aerobic respiration.
Aerobic respiration is a series of enzyme controlled reactions in which oxygen is needed to release chemical energy from glucose to form ATP
Which cellular processes can the engery produced in aerobic respiration be used for?
Muscular contractions active transport nerve impulses mitosis making proteins
Name the two stages of aerobic respirations?
the stages of aerobic respiration are:
1) Glycolysis
2) Pyruvate Breakdown
Describe Glycolysis?
It occurs in the cytoplasm.
Glucose is converted into 2 pyruvate molecules, this releases enough energy to yield two molecules of ATP
Describe pyruvate breakdown?
It occurs in the mitochondria
Pyruvate breaks down in the presence of oxygen to form carbon dioxide and water.
A large number of ATP molecules (36) are made from this stage
All stages are controlled by enzymes.
38 ATP molecules are produced across the two stages
what is the word equation for aerobic respiration
The word equation for aerobic respiration is:
glucose + oxygen —-> CO2, water and energy
What is anaerobic respiration (fermentation)
If oxygen is unavailable, anaerobic respiration takes place. Only 2 ATP molecules are made from glucose during this process
What is the word equation for fermentation in animals?
glucose —-> pyruvate —-> lactate
(2 ATP are produced in the glucose to pyruvate stage
What is the word equation for fermentation in plants/yeast?
glucose —-> pyruvate —-> CO2 and ethanol
