B1 Flashcards
What are the sizes od eukaryotic and prokaryotic cells ?
- Eukaryotic range from 10 micrometers to 100 micrometeres
- Prokaryotic range from 1 micrometer to 10 micrometeres
Which cells are more complex, eukaryotic or prokaryotic cells and what organisms do they make up?
Eukaryotic cells are more complex cells making up animal and plant cells
-Prokaryotic cells are simple cells mkaing up bacteria cells
What are the main structures in plant and animal cells?
Animal cells contain: -Nucleus -Cell membrane -Cytoplasm -Mitochondria Plant cells contian: -All of the above -Cell wall -Vacuole -Chloroplast
What are bacteria?
- The smallest living organisms
- Unicellular
- Usually 1 micrometer
Prokaryotes examples?
- E. coli - Causes food poisoning
- Streptococcus - Causes sore throats
- Streptomyces - found in cells, antibiotic created from them
What are the main stuctures of bacteria cells and their uses?
Main structures include:
- Chromosomal DNA - One long circular chromosome that controls cell activity, free floating
- Plasmids - Small extra loop of DNA,not part of chromosme. Antibiotic reistance
- Cell membrane - Control what goes in and out of cell
What are the other stuctures of bacteria cells and their uses?
- Flagella - Long tail like, helps movement through liquid
- Pili - Tiny, hairlike structures, enable attatching to structures, can transfer genetic material
- Slime capsule - Slime layer out of cell,stops drying out
Why do scientists stain cells?
Becuase some stains stain specific sub-cellular structures making them easy identify
What are some common stains and their uses?
- Methylene blue- Makes is easier to see nucleus of animal cells
- Iodine makes it easier to see plant cell nucleus
- Crystal violet - Stains bacteria cells wall
Whats total magnification using lens magnification formula?
Total mag = eyepiece lens mag * objective lens mag
Whats formula for magnification using image and real size?
magnification = image size / real size
What are the 2 types of electron microscopes and their uses?
- Transmission electron microscope - produce most magnified images, work in similar way to light microscopes, beams of electrons pass through sample and focuses making an image
- Scanning electron microscope - Makes 3D image of a surface. Beam of electrons sent across specimin surface and reflect making an imag
What are the advantages and disadvantages to the electron microscope?
Disadvantages: - Expensive to buy and operate - Large and difficult to move - Sample prep is complex - B&W images, false colour can be added - Specimens are dead - Large and hard to move Advantages: - Resolution up to 0.1nm
What are the advantages and disadvantage to the light microscope?
Advantage: - Cheap to buy and operate - Small and portable - Simple to prep a sample - Natural colour of specimen seen, unless stain is used - Specimens can be dead or alive Disadvantage: - Resolution only up to o.2 micrometer
What does DNA contain?
- All of an organism’s genetic material - the chemical instructions it needs to grow an develop
How is DNA arranged/
Into chromosomes
What are chromosomes?
- Long molcecules of coiled up DNA
What are genes?
- Short sections of DNA that code for a characteristic, eye colour
- The code a gene contains causes specific proteins to be made, these particular proteins determine the cells function
- E.g: Protein haemoglobin found in red blood cells. Binds to O2, red blood cells transport this round body
What controls how an organism functions and how it looks?
- The combination of genes
- E.g genes determine blood group, freckles or dimples
What is the shape of DNA?
- Double helix, double strand spiral
What is a single strand of DNA made up of?
- Lots of nucleotides joined in a long chain
- This makes DNA a polymer
What does each nucleotide contain?
- A deoxyribose sugar, phosphate group and a base
- Arranged in phosphate-sugar-base
What do all nucleotides in DNA have in common?
- They have the same sugar and phosphate group
What do bases in DNA do?
- They form cross links with the bases from the other strand
- This keeps both strands tightly wound together
What is complementary base pairing?
A-T. adenine-thymine
C-G cytosine-guanine
What are polymers?
- Polymers are large complex molecules composed of long chains of monomers joined together
What are monomers?
- Small basic molecular units
How is DNA a polymer?
- It is made up of nucleotide monomers
Why is a copy of DNA made in protein synthesis?
- The DNA is too big to leave the nucleus of the cell and enter the cytoplasm
- So copy DNA is made, a single strand mRNA
What is the process in which mRNA is produced?
- Transcription
What happens in transcription(mRNA production)?
- DNA around a gene unzips, both strands seperated
- One of the strands acts as a template
- Complementary bases attach to strand being copied
- No thymine in mRNA, uracil binds with adenine
mRNA detatches from DNA
What happens after mRNA is produced?
- Its small enough, so it moves out of nucleus
- Travels to subcellular structure, ribosomes in cytoplasm
What are the ribosomes?
A subcellular structture in which proteins are made
What is the process in which proteins are made known as?
Translation
What determines what proteins are produced?
- Order of bases in a gene that decides order of amino acids in a protein
How does ribsosome make proteins ( in simple terms)?
- mRNA attaches to a ribosome
- Nucleotide sequencce in interpreted and protein is made
Describe the whole process of translation?
- Ribosomw reads mRNA nucelotides in codons or triplet codes, these all code for a specific amino acid
- Ribosome keeps reading codon adding more amino aicds, which join to make a protein
What are enzymes?
- Proteins that are biological catalysts, they speed up a reaction without being used up
Instead of using enzymes why cant you just increase the temperature of the cell?
- While increase in temp increases reaction rate, it can also increase the speed of unwanted reactions
- If temp increases too much, it damage the cell
What is an advantae to an enzyme?
-Decrease the need for high temps in the body
What are 2 uses of biological enzymes?
- Build larger molcules form smaller ones, protein synthesis
- Break down larger molecules into smaller ones, digestion
Why are enzymes not all identical?
- Each is a protein, made of long amino chians folded for a specific shape
- Each enzyme has a different use
What is the molecule that binds to an enzyme and where does it bind?
- Substrate and it binds to the active site
Why do enzymes not bind to all molecules?
- Enymes are highly specific, so they can only bind to 1 type of substrate
- SUbstrate must fit exactly in active site of the enzyme or molecule dosen’t bind
What is the high specifity of an enzyme known as ?
- The lock and key hypothesis
What is changed in the reaction, enzyme or substrate?
- Substrate
What happens if substrate shape dosen’t match the active site shape?
- The reaction wont be catalysed and substrate won’t change
What is the section of DNA that codes for a particular protein called?
- Gene
How does change in temperature affect rate of enzyme-controlled reaction?
- Initially increases rate of enzyme controlled reaction until enzyme denatures, which reduces rate of reaction till 0
Initially, why does increse in temperature increase rate of enzyme controlled reaction?
- At higher temp, enzyme and substrate molecules move faster and collide more often
What happens to enzymes if temperature becoms too high?
- Amino acid chains start to unravel, changing shape of active site - denaturing enzyme
What happens when an enzyme is denatured?
- It loses shape so substrate dosen’t fit in active site anymore
- So, enzyme can’t catalyse reaction and reaction slows down
- They can’t return to original shape
What are the factors that affect enzyme controlled reactions?
- pH
- Temperature
- Enzyme and substrate concentration
How does pH affect rate of enzyme controlled reactions?
- If too high or low, it interferes with bonds holding enzyme together, which changes shape of active site and irreversibly dennature enzyme
How does enzyme concentration affect rate on enzyme controlled reactions?
- More enzymes present, more likely a substrate will meet up and join with one and join with it, increase in enzyme conc, increase rate of reaction
- If substrate amount limited, theres a point where enough enzymes to deal with available substrate, so adding more has no further effect
How does substrate concentration affect rate of enzyme controlled reactions?
- Higher substrate concentration, faster reaction is more likely it meets up with an enzyme and react
- Only upto a point, as there are too many substrate molecules for enzymes, all active sites full
What are carbihydrate molecules made of/
- monomers that are simple sugars, they join in log chains to make polymers, large complex carbs
What and how can carb polymers be broken into?
- Polymer broken down back into suagrs by carbohydrase enzymes
- Starch broken by amylase
What enzye breaks down proteins?
- Protease
What monomers make up prtoein?
- Amino acids
What are lipids?
- Fats and oils
What are lipids synthesised from?
- 3 fatty acid molecules and a gycerol molcule
What enzyme breaks down lipids?
- Lipase
What do lipase enzymes break lipids down into?
- Fatty acids and glycerol
What happenes when food molecules are fully digested?
- They’re absorbed into bloodstream and travel to cells that need them
What is respiration?
- Proccess of transferring energy from breakdown of glucose, happens in every cell - a universal chemical process
Why is ATP made in respiration?
- Energy transferred by respiration can’t directly be used by cells - its used to make ATP
- ATP stores energy needed for many cell processes
What is respiration controlled by and how does this affect it?
- Controlled by enzymes, so rate of respiration affected by both temperature and pH
Cells can respire using glucose as a substrate, what other things can be used as a substrate?
- Organism can break down organic molecules to use as substrate in respiration
How is ATP that’s produced in respiration used?
- To synthesis larger molecules form smaller ones to make new cell material
- For movement, as it can be used tocontract muscle to move
- To stay warm
What do the number of mitochondira in a cell tell you?
- How active the cell is
Do muscle cells have a lot of mitochondria and why?
- Yes, becuase they transfer a lot of energy, so they have large quantity of mitochondria
Do liver cells have a lot of mitochondria?
- Yes because they carry out many reactions
When does anaerobic respiration take place?
- When there isn’t enough oxygen present
Why during sternous excersize is there not enough oxygen present?
- Your heart rate cannot increase fast enough tommet the demand of oxygen required
How is glucose broken down during anaerobic respiration?
- It is partially broken down and lactic acid is produced
How much ATP is produced in anaerobic and aerobic respiration?
- Aerobic - 32ATP
- Anaerobic - 2ATP
What is an advantage of anaerobic respiration?
- You can atleast continue to use your muscles
What happens after anaerobic respiratoin?
- After you stop excersise you will have an oxygen debt, the extra oxygen required to break down all the lactic acid built up to allow aerobic respiration after
Can plants respire anaerobically?
- Under some conditions they can if no O2 present like in waterclogged soils
What does anarobic repsiration in plants and fungi make?
- Ethanol and Carbon Dioxide
Where does plant get reactants required in photosynthesis from?
- Carbon dioxide diffues from air into plant through stomata
- Water enters from soil through rooh hair cells by osmosis
What is some of the gluose made in photoynthesis used for?
- Making larger, complex compounds that plants and alage need to grow
Where does photosynthesis in a plant occur?
- In plant’s chloroplasts - they contain cholorphyll which absorbs light
- Mainly in leaf but a little in lpant stem
How is chlorophyll related to photosynthesis?
- Light transfers energy to chlorplats where CO2 and H20 react to make glucose
What are 2 stages of photosynthesis?
- Stage 1, Light dependant, energy transferred from light splits water to O2 gas and hydrogen ions
- Stage 2, Light independant, carbon dioxide combines with hydrogen ions to make glucose
What happens to the glucose made in photosynthesis that isn’t used right away?
- Converted into starch - provides a store of energy that can be used at night for respiration
What are the factors that affect rate of photosynthesis known as?
- Limiting factors - CO2, temp, light intensity
How to calculate rate of photosynthesis?
Rate = 1/time
unit - s^-1, min^-1, h^-1
How does light intesity affect rate of photosynthesis?
- Light transfers energy needed for photosynthesis
- As light level increases, photosynthesis rate increases steadily upto certain point
- At that point, it wont make a difference temp or co2 s limiting factor
What is the relationship between distance from lamp and light intensity ?
- They are inversly proprtional and this is known as the Inverse square law
What is formula for inverse square law?
Light intensity = 1/distance^2
How does CO2 affect rate of photosynthesis?
- It is one of reactans for photosyntheis
- Greater CO2 conc highet rate oh photosynthesis
- It is also usually the limiting factor
How does temperature affect rate of photosynthesis?
Photosyntheis is a series of enzyme controlled reactions, higher temp, higher rate of reaction
- Stops at certain point as if temp is too high, enzymes will denature
