GCSE biology 1

Plant & Animal cells= eukaryotes and have:

-cell membrane

-cytoplasm

-nucleus (genetic material enclosed)

Bacterial= prokaryotes (smaller) and have:

-cytoplasm

-cell membrane & wall

-DNA loops (not in nucleus, float in cytoplasm)

-small rings= plasmids

Animal cells have:

-nucleus

-cytoplasm

-cell membrane

-mitochondria

-ribosomes

Plant cell same but also have:

-chloroplasts

-vacuole(filled with cell sap)

-cell wall(made of cellulose)

Structure of different cells made for different functions

cells can be in:

-tissue

-organ

-organ system

-whole organism

Specialised Animal cells                            Specialised plant cells

-sperm cells                                                 -Root hair cells

-nerve cells                                                   -Xylem cells

-muscle cells                                                -Phloem cells

Cells diffrentiate to become different cells (IMPORTANT)

Animal cells

-diffrentiate at early stage

Plant cells 

-able to diffrentiate throughout life

Mature Animal- diffrentiate for repair and replacement

diffrentiation requires different sub-cellular structures to carry out function

Microscopes develop over time (increase understanding of things unable to be seen with naked eye -subcellular structures-)

Electron microscopes help see subcellular structures

Light microscope limited with magnification and resolution

Electron Microscope:

-higher resolution & magnification

-used to study cells in finer detail

-enable biologists to see & understand cells

Bacteria multiply though binary fission (under right temperature conditions)

Bacteria grow in nutrient broth/ agar gel

Used for investigating antibiotics & disinfectants

Uncontaminated culture (aseptic techniques):

-petri dish sterilised

-innoculating loops are flamed (sterilised)

-lid secured with tape 

-stored upside down

-incubated at 25 degrees celcius

Nucleus contains chromosomes

Chromosomes made of DNA molecules

Chromosomes have genes

Chromosomes found in pairs in body cells

Cell divides in stages (cell cycle)

One stage of cell cycle= Mitosis

Genetic material doubled and divided into two daughter cells (identical)

Before division:

-cells grows

-increase number of sub-cellular structure (ribosomes & mitochondria)

-replicate to form 2 of each chromosome

Mitosis one set of chromosomes pulled to each end & nucleus divides

Cytoplasm & cell membrane divide to form to cells

IMPORTANT FOR GROWTH AND DEVELOPMENT

Stem cell= undiffrentiated cells (can become another cell)

Human embryos= cloned for different types of human cells

-same genes as patient (so not rejected by patient

-risk of viral infection, ethical or religious objection

Adult Bone Marrow= other types of cell (blood cells)

Meristem Tissue= diffrentiate into other plant cells throughout life

-clones of plant cells quickly & economically

-save rare species from extinction

-crop plants with disease resistance cloned to produce large number identical

Treatment for diabetes or paralysis

Substance move in and out of cell through cell membrsne

Diffusion= spreading out of particles (net movement) from high concentration to low concentration

uses

-oxygen and carbon dioxide (gas exchange)

- waste product urea into blood plasma for excreation through kidney

Factors

-concentration gradient(difference in concentration)

-temperature

-surface area of membrane

Single celled organism= larger surface area= sufficient transport of molecules in & out

Water moves across membranes

Osmosis= diffusion of water from dilute to concentrated solution through patially permeable membrane

Movement of substances from dilute to concentrated solution

requires respiration for energy

Allow mineral ions to be absorbed into plant root hairs from soil (dilute)

ions keep plant healthy

Allows sugar molecules to be absorbed from gut (low conc.) to blood (high conc.)

Sugar used for cell respiration