Biology ELLIE RYAN 9B

Name two groups of cells

Prokaryotic and eukaryotic cells

Prokaryotic cells info

Smaller (cell membrane, cytoplasm and cell wall and NO nucleus), genetic material not in a nucleus- single DNA loop and may contain small circular DNA called plasmid

Example of a prokaryotic cell

Bacteria

Diagram of a bacteria cell

Genetic information, cytoplasm, cell membrane, slime capsules*, cell wall, plasmids, flagella* (* not always included)

Eukaryotic cells info

More complex (cell membrane, cytoplasm- may or may not have a cell wall), have a nucleus which contains the genetic information

Example of eukaryotic cells

PLANT CELL Cell membrane, ribosomes, cell wall, mitochondria, cytoplasm, permanent vacuole, chloroplast and nucleus

Example of eukaryotic cells

ANIMAL CELL Cell membrane, ribosomes, mitochondria, cytoplasm and nucleus

Ribosomes

Protein synthesis

Mitochondria

Site of aerobic respiration (release of energy)

Nucleus

Controls cell activity - contains genetic material

Cell membrane

Controls movement of substances in and out of cells

Cytoplasm

Liquid gel where most of cell reactions happen (e.g anaerobic respiration)

Cell wall

Cellulose for strength (algae have too)

Chloroplast

Contain chlorophyll for photosynthesis

Vacuole

Contains cell sap - keeps it rigid

The difference between chlorophyll and chloroplast

Chloroplast is the organelle structure- chlorophyll is the green pigment that absorbs sunlight

As an organism develops

Cells differentiate to form specialised cells

What is a specialised cell

A cell that has got different sub-cellular structure, so its structure is linked to its function- specific to its job

What are examples of specialised cells in animals

Nerve cells - long axons to carry electrical impulses over long distances, special ends that release chemicals to transfer messages to other nerves, lots of mitochondria to release energy from respiration

Muscle cells

Many mitochondria for high rate of respiration to contract, stores of glycogen as energy source for respiration

Sperm cells

Tail to swim towards egg, mid-section has lots of mitochondria to release energy for respiration, acrosome (head)has enzymes that breakdown egg layers to gain access.

Examples of specialised cells in plants

Root hair cells - have extensions (hairs) to increase SA for fast absorption of water/nutrients, many mitochondria to provide energy for active transport of nutrients against con gradient, have thin cell walls to provide a short diffusion/osmosis distance.

Xylem cell

Long hollow dead tube cells for fast movement of water up the plant, cell wall strengthened with lignin

Phloem cells

Special sieve holed walls to allow movement of dissolved substances, no internal structure to obstruct flow

In mature animals, what is most cell division for?

Repair and replacement

When does cell division occur?

Animal - at early embryos stage, plants retain the ability to differentiate throughout life

Types of microscopes

Light and electron

Why is the electron microscope useful

To study cells in finer detail

Advantages of electron microscope?

Has a bigger magnification and better resolution

Resolution and magnification

Resolution- the ability to distinguish between two separate points which are close together, magnification = how many times bigger the object gets

The magnification equation

Magnification (m)= image size (I) x object size (o), image size = magnification x object size, object size= image size/magnification

What is it important to remember before using the equation?

Getting all the data into the same units

Labels of the light microscope

• eyepiece lens

• Coarse focus

• Fine focus

• High power objective lens

• Low power objective lens

• Slide stage

• Mirror

Orders of magnitude

10 times bigger = 10(1) bigger = 1 order

100 times bigger = 10(2) bigger = 2 orders

1000 times bigger = 10(3) bigger = 3 orders

How to work out how many time bigger objects are?

Divide the bigger number by the smaller one - answer should be 10,100,1000

What are three ways substances can move

Diffusion, osmosis and active transport

Why do substances need to move

Life processes need gases and other dissolved substances before they can happen.

E.g respiration requires glucose and oxygen to be inside cells

Photosynthesis requires carbon dioxide and water to get into the plant

What is diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Down the concentration ( high concentration to low concentration).

Passive process - require no energy

Occurs until equilibrium

Examples of diffusion

• oxygen from the air into the bloodstream

• Co(2) from the bloodstream into the air

• Oxygen into cells do body from the blood to supply respiration

• Carbon dioxide into actively photosynthesising cells

What causes diffusion

• passive - no energy required: relies on molecules moving randomly due to the energy they have

Factors that affect the rate of diffusion (ROD) and what makes diffusion quicker

• difference in concentration - the larger concentration gradient = faster ROD

• Temperature/thermal energy- higher temperature = faster ROD

  • Surface area - larger SA = faster ROD

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.

Down the concentration gradient (high concentration to low concentration)

Passive process- requires no energy

Occurs until equilibrium

A high concentration of water is also known as

dilute solution

A low concentration of water is known as

A concentrated solution

importance of osmosis in plants

To keep tugor of cell - vacuole fills with water and cell becomes hard and rigid

What is active transport

• the movement of molecules from an area of low concentration to high concentration

• Against the concentration gradient

• Active process- requires energy

Example of active transport

• glucose from low concentration in small intestine into the blood

• Glucose re-absorption in the kidney

• Uptake of mineral ions in the root of plants

Genetics size rule

cells contain nucleus, which contain chromosomes, which are made up of genes, which have a genetic code nahe from the molecule DNA

What are chromosomes

structure of inheritance- made up of many genes

what are genes

section of DNA that codes for a particular trait

what are alleles

Different versions of a particular gene, eg blue eyes or green eyes

what is DNA

Deoxyribonucleic acid- the molecule of inheritance = the genetic code

what shape is DNA

double helix

what is the genetic code used for

to combine amino acids in a specific order to make proteins such as enzymes

in humans, how many chromosomes do cells have

normal body- cells 46 gamete 23

what are gametes

the sex cells, sperm or egg

why do most organisms have an even number of chromosomes

they occur in pairs, one inherited from each parent

the pairs are called?

homologous pairs- two of each chromosome

what does this mean

we have two copies of each gene

what is cell division

a cell splitting its nucleus and membrane to create new cells

what are the two types

mitosis and meiosis

what is mitosis

the production of two genetically identical cells from an original cell which have the same numbers of chromosomes

what is it important for

growth, tissue repair and replacement

what happens during mitosis division

DNA replicates and divides once

what is the cell cycle

series of stages that cause cells to divide

stages of the cell cycle

1. cell grows and makes more mitochondria and ribosomes, DNA replicates

2. one set of chromosomes moves to each end of cell, nucleus divides (mitosis)

3. cytoplasm and cell membrane divides to form two genetically identical cells

what are stem cells

in specialised cells that can differentiate into any specialised cell of an organism

what is differentiation

stem cells becoming specialised- being assigned a specific job

when does differentiation happen in animals

manly during early stages of development in womb

in plants

they keep some stem cells even whah mature in their meristem tissue (root and shoots)

what can stem cells be used for in plants

cloning plants - creating genetically identical plants for research, horticulture and agriculture protecting rare species from extinction

human stem cells- sources

embryonic stem cells- human embryos

adult stem cells- bone marrow

problems with adult stem cells

keeping some specialism and so cannot be made to differentiate into all types of cells but can turn into lots of cells including blood cells

human stem cell use

cloned to differentiate into cells tissue organs for medical therapy

examples

nerve cells - paralysis

pancreatic cells - diabetes

organs - e.g kidney for transplant

heart cells - heart attack recovery

how are these cells made

embryo is produced with the same genes as the patient - this means that the cells tissue organs are not rejected by the patient’s immune system

Evaluation of stem cell therapy

Pros: reduce suffering by treating diseases/ save NHS money/ no rejection issues

Cons: expensive and not always effective : ethical issues with discarding embryos / possible transfer of viral infections

Summary: the high cost spent research a developing the treatment will be outweighed by saving to NHS once treatment is established so i think its a good idea.

what is health

a state of physical and mental wellbeing

what are the types of diseases

non communicable diseases and communicable diseases

what is the difference

communicable is infectious

what else can meal us ill

diet - overeating= risk of type 2 diabetes

stress - linked to heart disease/ cancer

life situations- where you live = access to medication

example of NCD

Coronary heart disease, stroke, COPD (chronic obstructive pulmonary disease)

what contributes to NCD

risk factors- aspects of a person lifestyle or substance present in a person body/environment that have been shown to be linked to an increased rate of disease

most diseases

are cause by the interaction of the numbers of factors

what is a casual relationship ( but we’re knee deep in the passenger seat and you’re eating my out)

for some ncd have been proved that a certain risk caused the disease

if there is no casual relationship what do we describe the increase risk as?

a correlation- as a risk factor increases so does disease however correlation is not causation another factor may be involved eg genetics

how can different types of diseases interact

defect the immune system means you are more likely to to suffer infectious disease

viruses living in cells can be triggers for cancer (eg HPV - cervical cancer)

immune reactors caused by a pathogen can trigger allergies (asthma/ rashes)

what are the known risk factors for disease

• the effects of diet smoking and exercise on cardiovascular disease

• obesity as a risk factor for type 2 diabetes

• the effects of alcohol on the liver and the brain function

• the effects of smoking on lung disease and lung cancer

• the effects of smoking and alcohol on unborn babies

• carcinogens, including ionising radiation, as a risk factor for cancer

what do you need to be aware of in terms of effects of non-communicable diseases

the human cost (death) the financial cost (treatment) for an individual, community, nation or globally

explain the effects of poor diet?

a poor diet increases your risk of developing cardiovascular disease directly through cholesterol levels caused CAD and indirectly through obesity (body stress of being overweight)

what is the effect of exercise

reduces the likelihood of developing cardiovascular disease

obesity is a strong risk factor for

type 2 diabetes

explain the effects of high alcohol consumption

alcohol is toxic and damages the liver causes cirrhosis and liver cancer- it also causes brain damage and can affect unborn babies’ development

explain the effects of smoking

smoking causes cardiovascular disease including coronary heart disease, lung cancer and COPD

if a foetus is exposed to smoke?

has restricted oxygen levels and carbon monoxide takes the place of oxygen in red blood cells this leads to low birth weight premature and still birth

what is cancer

a change in cells that lead to uncontrolled cell growth and division. uncontrolled cell growth can cause cancers to grow very large

what changes in a cancer cell

• the DNA in the nucleus

• this change in called a mutation

what are the two types of tumours

benign and malignant

features of benign tumours

• growth of abnormal cells which are contained in one area usually within a membrane

• they do not invade other parts of the body

features of a malignant tumour

• generally referred to as cancers

• some of the cancers cells split off and travel to different parts of the body in the blood

• they settle in different organs and form secondary tumors