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