Cell biology

light microscope

An optical instrument with lenses that refract (bend) visible light to magnify images of specimens. ( cheap , weaker resolution

Resolution

minimum distance two points can be apart and still be distinguished as two separate points , how clear the image is

Types of microscopes

light, electron, scanning, transmission electron

Electron microscope

microscope that forms an image by focusing beams of electrons onto a specimen ( 10 million magnification)

What do you get from a scanning electron microscope

Black and white images of the outside

What do you get from a transmission electron microscope

To see through cells and see organelles

Why is electron microscope better

Able to study the interior of cells and organelles in more detail with better magnification

Magnification

How much bigger an image appears compared to real life

Magnification equation

magnification = image size/actual size (I AM)

total magnification equation

total magnification = eyepiece lens magnification x objective lens magnification

Parts of a microscope

eyepiece, objective lens, fine adjustment know, course adjustment knob, stage, stage clips,

coarse adjustment knob

Moves the stage up and down for focusing

fine adjustment knob

Moves the stage slightly to sharpen the image ( resolution)

micro/meter

10^-6

Nanometer

10^-9

Most animal and plant cells are

0.01 - 0.10 mm in size

How to carry out the microscope practical

- set up the microscope on the lowest magnification and the mirror reflecting the light towards the lens

- Then peel a single layer of onion tissue and place it on the slide and put 2 drops of iodine solution before putting the cover slip on the slide and under the microscope

- Slowly lower the stage until the image focuses

- change magnification lens

Parts of an animal cell

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

Parts of a plant cell

Nucleus, Vacuole, Ribosome, Cell Membrane, Mitochondria, Cell Wall, Chloroplast, cytoplasm

Cytoplasm

A jellylike fluid inside the cell where chemical reactions occur

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

cell membrane

A cell structure that controls which substances can enter or leave the cell.

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production. , where most energy is released in respiration

Ribosomes

site of protein synthesis

Chloroplast

Site of photosynthesis

Cell wall

A rigid structure that surrounds the cell membrane and provides support and strength to the cell

Vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates , cell sap is stored

Parts of bacteria cell

Cell membrane , circular loop of dna , plasmid , ribosomes , cytoplasm, cell wall made from peptidoglycan

Eukaryotes

organisms made up of one or more cells ( multicellular) , evolved later than prokaryotes, e.g animal and plant cells , bigger than prokaryotes

Prokaryotes

Single-celled organisms ( unicellular)

E.g bacteria and archaea , evolved 4 billion years ago

mm to micrometers

x1000

Micro meters to nano meters

X 1000

Adaptions of the sperm cell

Function: to get male DNA to the females egg

1) a sperm cell has a long tail so it can swim to the egg

2) It has a lot of mitochondria in the middle section to provide the energy needed to swim the distance

3) It has an acrosome at the front of the 'head' where it stores enzymes needed to digest it's way through the membrane of the Egg cell

Adaptations of Nerve Cells

- long axon which carries electrical impulses from one part of the body to another

- axon is covered in myelin which insulates axon speeding up transmission of nerve impulses

- end of axon has synapses

- dendrites increases surface area so nerve cells can connect easier

adaption of root hair cell

large surface area

Stem cells

Undifferentiated cells capable of differentiating into specialized cells

Embryonic stem cells

An undifferentiated cell, taken from an embryo that has potential to give rise to various other cell or tissue types

adult stem cells

stem cells that are found in adults that can differentiate and form a limited number of cells

meristem cells

Undifferentiated plant cells capable of rapid cell division and can differentiate into all cells of the plant

What can we use stem cells for ?

We can use stem cells to treat many disease and to help regain the 5 senses and to treat paralysis

rejection

A new cell added to a person is recognised as foreign and therefore trigger an immune response in the body

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

- found in nucleus of eukaryotic cells , cytoplasm of prokaryotic

- double helix structures

- deoxyribonucleic acid

- chemical

Chromosomes

threadlike structures made of DNA molecules that contain the genes

Gene

A segment of DNA on a chromosome that codes for a specific trait

Genes determine

characteristics of an organism

DNA found in order

Nucleus— Chromosome- genes

Body cells have how many chromosomes?

46 chromosomes, 23 pairs

sex cells (gametes) have how many chromosomes

23

cell cycle

series of events that cells go through as they grow and divide

Mitosis

mitosis is a type of cell division that produces two genetically identical diploid daughter cells from a single parent cell

What happens if the cells are not regulated properly?

You can get cancer cells

Interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases , DNA is being copied

Why does the cell cycle have checkpoints?

prevent damaged cells from replicating

What happens if a cell does not pass a checkpoint?

apoptosis - self destruction of cells or waits to repair itself if fault is repairable

Purpose of mitosis

growth and repair

Stages of Mitosis

•Interphase - dna is replicated or copied

•Prophase - the chromosomes are visible and are in the nucleus

•Metaphase.- the nucleus has broken down which allows the chromosomes to move to the middle

• Anaphase - the chromosome are being pulled apart to opposite sides of the cell

• Telophase - Two nucleui , one around each set of chromosomes have been formed

• Cytokinesis ( after mitosis) - The cell membrane and cytoplasm divide to form identical daughter cells

Differentiation

process in which cells become specialized in structure and function

What are the problems of using embryonic stem cells ?

Ethically tricky and they come from human embryos some say taking embryonic stem cells is destroying potential life

Meristems can be used

To clone plants quickly and cheaply and modify plants to withstand environmental challenges, helping preserve endangered species of plants

therapeutic cloning

The cloning of human cells by nuclear transplantation for therapeutic purposes, such as the generation of embryonic stem cells to treat disease.

How to culture bacteria

- Clean your workspace

- sterilise the inoculated loop in a Bunsen burner flame

- use the inoculated loop to transfer bacteria onto the agar jelly evenly

- only raise the lid slightly open to get to the agar jelly

- once the bacteria is on the agar jelly tape the sides of the Petri dish

- incubate the Petri dishes at 25 degrees to reduce the growth of harmful bacteria

Tumour

a group of cells that have divided uncontrollably

2 types of tumors

benign and malignant

benign tumor

non-cancerous, can't spread ( contained in a membrane) , slow growing

Malignant tumour

cancerous, fast-growing, spreads easily. , can travel in bloodstream

Main treatments of cancer

surgery, radiation, chemotherapy

Side effects of cancer treatments

- hair loss

- pain

- general sickness

- weakness

- vomiting

Risk

The chance of loss from an event that cannot be entirely controlled

cancer risk factors

• Diet

• Cigarette smoking

• Excessive alcohol use

• Exposure to UV

• Genetics

• stress

• vaping

• radiation

Why do we culture bacteria?

To investigate the effects of chemicals such as disinfectants and antibiotics , experiments , new treatments, discover how bacteria can benefit or harm us .

Why do schools store culture bacteria at 25°C

Stop the growth of harmful bacteria

How to calculate mean division time ?

Because bacteria divides into 2 in 30 mins count how many 30 mins in time given then put that number as indices of 2

Colony

A group of bacteria that has multiplied

binary fission

A form of asexual reproduction in single-celled organisms / prokaryotes ( bacteria ) by which one cell divides into two cells of the same size.

- in order for a bacteria cell to divide it needs to grown and replicate genetic material

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration, down the concentration gradient.

If diffusion passive or active

Passive

passive

does not require energy

Things that alter rate of diffusion

1. Steepness of concentration gradient

2. Surface area to volume ratio

3. High temperature

4. The diffusion distance

How surface are to volume ratio effects diffusion

small animals have a higher surface area to volume ratio so diffusion takes place faster whereas larger animals like elephants have a smaller surface area to volume ratio and so diffusion is slower

Osmosis definition

Is the movement of water particles from a more dilute solution ( higher concentration) to a more concentrated solution ( low concentration) through a partially permeable membrane.

Example of osmosis

Plants absorb water from the soil into their roots which in turn moves up the stem to the leaves where it is used in photosynthesis

Example of diffusion

Oxygen moves from the alveoli to red blood cells

flaccid

, lose water by osmosis , shrink, pull away from cell wall and become flaccid

turgid cell

a plant cell that has absorbed water and has cytoplasm that is pressing outwards on the cell wall . Cell wall stops cell bursting when gains water by osmosis

hypertonic solution

A solution in which the concentration of solutes is greater than that of the cell that resides in the solution , water leaves the cell by osmosis becomes flaccid

hypotonic solution

A solution in which the concentration of solutes is less than that of the cell that resides in the solution , water enters the cell by osmosis , plant cells become turgid while animal cells could burst

isotonic solution

A solution in which the concentration of solutes is essentially equal to that of the cell which resides in the solution, no water movement

Investigating osmosis experiment:

Cut potatoe up into cylinders using a cork borer on the white tile and measure the cylinders to 2cm each . Weigh each of the cylinders for each solution and write down the starting masses after patting them on a paper towel . Measure 10ml of each solution and then put the cylinder in the tubes with different sugar solutions. After 20 mins measure the cylinders on a mass balance after drying the excess water off and write down the end masses . Calculate the change in mass percentage. ( change in mass / starting masses x 100)

Active transport

the movement of particles against a concentration gradient and requires the cell to use energy

active transport example

Root hair cell absorption of mineral ions