N5 Flashcards
Function of the nucleus
Controls all cell activities and contains DNA
Membrane function
Controls what substances can enter and leave the cell
Cytoplasm function
Where chemical reactions happen
Cell walls function
Gives cell shape and support
Vacuoles function
Stores cell sap
Mitochondria function
Site of aerobic respiration
Plasmid function?
Circular ring containing DNA
In what cells can a nucleus be found?
Animal
Plant
Fungi
What cells can the membrane be found in
Animal
Plant
Fungi
Bacterial
What cells can the cytoplasm be found in ?
Anima
Plat
Bacterial
Fungi
In what cells can a cell wall (with cellulose) be found in
Plant
In what cells can a cell wall (without cellulose) be found in
Bacteria
Fungal
In what cells can vacuoles be found in
Plant
Fungi
In what cells can mitochondria be found in
Animal
Plant
Fungi
In what cells can ribosomes be found in
Animal
Plant
Bacteria
Fungi
In what cells can plasmids be found in
Animal
Plant
Bacteria
Formula for calculating size of cells
Length/breadth divided by number of cells
What is the cell membrane composed of
Phospholipids and proteins
What 2 words would be used to describe a cell membrane
Selectively permeable
Define selectively permeable ?
It only allows the movement of some substances into the cell like small cells that can fit through
What is diffusion?
The movement of molecules down a concentration gradient from a higher concentration to a lower concentration
Why is diffusion important cells
It helps provide the cell with raw materials and helps to remove waste products
What enters the cell during diffusion
Oxygen and amino acids
What leaves the cell during diffusion
Carbon dioxide and urea
What is osmosis
The movement of water molecules from a higher water concentration to a lower water concentration. Through a selectively permeable membrane
What os active transport
The movement of molecules and ions from a lower concentration to a higher concentration against a concentration gradient
Active transport requires what and why
Requires energy to allow the proteins in the membrane to move the molecules against the concentration gradient
How would a DNA structure be described
A double stranded helix held by complementary base pairs
What are the 4 bases in DNA
Adenine
Thymine
Guanine
Cytosine
What do he bases in DNA form when put together
Complementary base pairs which means they only bond with certain pairs
A+t
G+C
What is a gene
A section of DNA which codes from a protein
What do long chains of amino acids make
Proteins
What do the sequence of bases determine
The amino acids sequence in proteins and the specific protein to be made
What is MRNA?
A molecule which carries complementry copy of the genetic code from the DNA in the nucleus to a ribosome where the protein is assembled from amino acids
Where are proteins made?
Ribosomes
What are the functions of proteins
Structural proteins - make p cell structures such as membranes
Enzymes - act as biological catalysts
Hormones - act as chemical messengers between cells
Antibodies - involved in body defences
Receptors - found in cell membranes and recognise specific substances
How is genetic information transferred from one cell to another
By genetic engineering
What is genetic engeneering used to do
To allow a species to make a protein that is normally made by another species
What does genetic engeneering allow
Pieces of chromosomes to be transferred from one species to another which then allows the recipient species to make new proteins
What are the 5 stages of genetic engineering
1- identify the section of DNA that contains the required gene for the source chromosome
2-extract the required gene / extract plasmid from the bacterial call
3-insert required gene into bacterial plasmid
4-insert plasmid into host bacterial cell
5- this produces a genetically modified organism (GM)
How must the chemical energy stored in glucose be released
By all cells through a series of enzyme controlled reactions called RESPIRATION
What does the energy used from the breakdown generate
ATP
What can the energy transferred by ATP be used fr
Cellular activities
What are the cellular activities produced with the energy from ATP?
Muscle cell contraction
Cell division
Protein synthesis
Transmission of nerve impulses
Where does aerobic respiration take place
In living cells when oxygen is present
Word equation from aerobic respiration
Glucose + oxygen —>carbon dioxide + water + energy
Aerobic respiration is a series…?
Of enzyme controlled reactions
What are the 2 stages of aerobic respiration
Breakdown of glucose
Breakdown of pyruvate
What are the details of stage 1 of aerobic respirations
Does not require oxygen
Occurs in the cytoplasm
Breaks down glucose into 2 molecules of pyruvate
Releases enough energy to make 2 ATP
What are the details of the second stage of aerobic respiration
Requires oxygen
Occurs in the mitochondria
Breaks down pyruvate into carbon dioxide and water
Releases enough energy to make many ATP
When does fermentation take place
In the absence of oxygen the fermentation pathway takes place
What is the word equation for fermentation in plant and fungal cells
Glucose —> carbon dioxide + ethanol + energy
Is the process of fermentation in the plant and fugal cells reversible?
No
Word equation for fermentation in animal cells
Glucose —> lactate + energy
Where does respiration begin
The cytoplasm
Is the process of fermentation in animal cells reversible
Yes
What do repirometers do
Measure teh rate of respiration
What are enzymes
Biological catalysts that speed up chemical reactions
What happens to an enzyme after a reaction
Nothing they stay un changed
What is the substance called of which an enzyme acts on
A substrate
What is the site called that binds the substrate to specific molecules
Active site
Enzymes are …? Because the shape of their active site is …? To the shape of its specific substrate
Specific
Complementary
What is a degradation reaction
Is where one large substrate is broken down into smaller products
What is a synthesis reaction
Where small substances are built up into a large product
When are enzymes most active
In their optimum conditions
What can enzymes and other proteins be affected by
Temperature and pH
What temperature do enzymes normally work best in
37 degrees
Denaturing an enzyme does what
Changes there shape which will affect the rate of reaction
Why do enzymes denature
If they are exposed to an incorrect ph or temperature meaning the shape of the active site has changed
What is the word equation for photosynthesis
Light energy
Carbon dioxide + water ——> sugar + oxygen
What are the 2 stages of photosynthesis
Light reactions
Carbon fixation
Stage 1 of photosynthesis ? In order
-light energy from the sun is trapped by chlorophyll in the chloroplasts
-light energy is converted into chemical energy which is used to generate ATP
-water is split to produce hydrogen and oxygen
-oxygen diffuses from the cell
-hydrogen and ATP are taken to the next stage
Stage 2 of photosynthesis?
- a series of enzyme controlled reactions
- uses hydrogen and ATP with carbon dioxide to produce sugar
How is the sugar from photosynthesis used ( 3 ways )
-Broken down during respiration to produce energy
-converted into starch which acts as an energy store
-converted into cellulose which cell walls are made from
What is a limited factor
One that limits how fast a reaction can go if it is short supply
What are the 3 limiting factors
Light intensity
Temprature
Carbon dioxide concentration
What does the nucleus of a cell contain
DNA which is organised into chromosomes
What is the chromosome compliment of a human?
46
How many sets of chromosomes do humans have
23
What is mitosis
The process of cell division
What are new cells needed for
Growth and repair of damaged cells and maintains diploid chromosome complement
What is the process of mitosis’s in order
-nucleus contains long uncoiled chromosomes which are difficult to see
-chromosomes make copies of themselves and become visible pairs of identical chromatids
-chromosomes line up along the equator , spindle fibres form at thee poles and attach to the centromeres
-spindle fibers pull chromatids apart from opposite poles of the cell
-daughter chromosomes gather at the poles of the cells
-cytoplasm divides forming 2 daughter cells which have the same diploid chromosome number as the parent cell
Why is it important for daughter cels to be identical to the parent cell
It ensures that no genetic information is lost
What are stem cells (in animals)
Unspecialised cells which can divide in order to self-renew
What do stem cells have the potential to do
Become differnt types of cells ( stem cells are involved in repair and growth
What are the 2 types of stem cells
Embryonic stem cells
Tissue. Stem cells
Where are embryonic stem cells found and what is there potential?
Found in the very early stages in embryos
Have the potential to become nearly all cells in the body
Where can tissue stem cells be found and what are there responsibilities
Found in tissues and organs of the body
Responsible for repair and growth
What are the 3 types of cell types
Tissue
Organ
System
Explain tissues
A group of cells with similar structure and function that all work together to do a particular job
Explain organs
A group of differnt tissues working together to preform a specific job
Explain systems
A group of differnt organs that work together to do a particular jog
What does the nervous system consist of
Brain
Spinal cord
Function of the cerebrum?
Memory
Thought
Intelligence
Reasoning
Cerebellums function ?
Balance and muscle co ordination
Function of medulla
Breathing rate and heart beat
What carries mesages along neurons
Electrical impulses
What are the 3 types of neurons (nerves)
Sensory
Inter
Motor
Explain the sensory neuron?
Pass the info to the CNS rom a receptor in the senses
Explain the inter neuron
Operate within the CNS which processes information from the senses that require a response
Explain the motor neuron
Enable a response to occur at an effector
What do receptors do
Detect a sensory input/stimuli from the receptor in he senses
Where are effectors found and what do they do
Found in the muscles and glands
They carry out a response
What is a reflex
A fast response to protect the body from harm
What is a synapse
A tiny gap between neurons
What does the endocrine gland do
Releases hormones into the bloodstream
What are hormones
Chemical messengers
What are hormones ade of
Protein and specifically affect target tissues
How is a target tissue alone targeted
It has cells with complementary receptor proteins for specific hormones so only that tissue will be affected by these hormones
How is a continuous supply of energy gained
Through respiration
What 2 hormones re involved in controlling blood glucose levels
Insulin
Glucagon
Where is insulin produced
By the pancreas and is carried in the blood to the target organ , liver
What does insulin do
Causes teh liver to take up glucose from the blood and convert it to a storage carbohydrate called glycogen and therefore reduces the levels of glucose in the blood
Where is glucagon produced
By the pancreas
What does glucagon do
Causes the liver to convert the storage carbohydrate glycogen to glucose and therefore increases the levels of glucose in the blood
Upper epidermis function
A transparent layer which allows sunlight to pass through to the cells blow
Palisade mesophyll function
Closely packed cells which contain many chloroplasts the main site of photosynthesis
Spongy mesophyll function
A lawyer of cells that contain may airspace’s where water gets evaporated
Stomata function
Pores on the underside of the leaf which allow gas and exchange and escape of water Vapor
Guard cell function?
2 cells which control the opening of the stomata
Vein function?
Contains xylem and phloem for water and sugar transport
What is a cell that has 2 matching sets of chromosomes called
Diploid
What are sex cells called
Gametes
How many sets of chromosomes do gametes have
1 (haploid)
How do plants like flowers reproduce
The pollen is produced in the anther and the ovule is produced in the ovary they meet and reproduce
What are the 2 gametes in humans called
Sperm
Egg
What is fertilisation
The fusion of the nuclei of the 2 haploid gametes to produce a diploid zygote which divides into an embryo
What is variation
Differences that can be seen between individual members of a species
Describe continuous variation
Range of values between a minimum and a maximum
Controlled by more than one gene (polygenic)
Describe discrete variation
Measurements fall into distinct groups
Controlled by a single gene
What is an alleles
A different form of gene
What is a genotype
The alleles that you have for different characteristics
What is a phenotype
The outward physical appearance and depends on your genes type
Describe homozygous
Individuals that have 2 of the same alleles for a gene
Describe heterozygous
Individuals that have 2 different alleles for a gene
population
number of organisms of one species in an area
producer
green plants that make its own food using light energy by photosynthesis
consumer
eats other organisms to obtain energy
herbivore
only eats plants material
