Cells Flashcards
Specialised cells
Have adaptations which help them carry out a specific function
Differentiation
The process in which a cell becomes specialised
Sperm cell job
Join with an egg cell in fertilisation
To combine genetic information
Sperm cell adaptations
Contain half genetic information in their nucleus
Long tail to swim to ovum
Packed with mitochondria = energy to swim
Enzymes at top of head to digest outer layer of ovum
Nerve cell function
Send electrical impulses around the body via the axon (long stick bit)
Nerve cell adaptations
Axon insulated by MYELIN to speed up transmission of nerve impulses
Has synapses for impulses to pass from one nerve to next
Dendrites to increase surface area = connect easier
Muscle cell jobs
Can contract for movement
Muscle cell adaptations
Protein fibres to change length (shorten) when contracted = decrease length of cell
Packed with mitochondria to provide energy via respiration
Form muscle tissue together
Root hair cells job
Increase surface area of the root by acting as hairs to absorb water + minerals more effectively
Root hair cell adaptations
Root hair to increase surface area
No chloroplasts because don’t photosynthesise
Xylem cells job
Found in stem as long tubes
Carry water and dissolved minerals from roots to leaves
Xylem cells adaptations
Thick walls w lignin to support the plant
Dead xylem cells because they’re sealed by lignin
Broken down end walls to from the long tube so minerals can flow easily
No internal structure (nucleus, cytoplasm, vacuole) = water and minerals flow easily
Phloem cells job
Carry dissolved sugars up and down the plant
Phloem cells structure
Phloem vessel cell
Sieve plates at end walls with pores
Companion cells connected by pores
Phloem cells adaptations
Vessel cell have no nucleus only limited cytoplasm and sieve plates with pores at end so sugars move through interior
Companion cells with mitochondria to respire for energy = can move the sugars
Eukaryotes
Cells that contain genetic information enclosed in a nucleus
What are the common features of ALL eukaryotes?
Nucleus
Cell membrane
Cytoplasm
Usually larger than prokaryotes
Eukaryotes examples
Animal cells + plant cells
Prokaryotes
Genetic material isn’t enclosed in a nucleus
How is genetic information arranged in a prokaryote?
A single loop of DNA
And maybe small rings called plasmids
What are common features of prokaryotes? (Bacteria)
Smaller than eukaryotes
Genetic info in a loop and plasmids (non membrane organelles)
Cell membrane and cell wall
Cytoplasm
Divide by binary fission
Stem cells
Undifferentiated cell that can divide to from more stem cells
And can differentiate to form specialised cells
Embryonic stem cells
Stem cells formed when a zygote begins to divide and form other stem cells
Haven’t differentiated yet but can to form any type of specialise cell
Adult stem cells
Stem cells that are present in non embryos but limited in differentiation
Where can adult stem cells be found?
Bone marrow
Eyes
Brain
Blood
Bone marrow transplants (leukaemia)
Cancer of bone marrow
Use radiation to destroy existing bone marrow
Transplant bone marrow from donor
Stem cells in bone marrow divide = new bone marrow
Differentiate to from new blood cells
Problems with bone marrow transplant
Donor must be compatible otherwise WBCs produced by transplanted marrow might attack patients body
Risk of viruses passing
Therapeutic cloning
Producing an embryo with same genetic information as patient to create embryonic stem cells
That can be transferred then differentiated to replace harmed cells in the patient
Therapeutic cloning steps
Egg cell from donor with no nucleus + nucleus from patient with their genetic info
= egg cell stimulated to divide
= embryo
Remove stem cells for therapeutic use
Benefits of therapeutic use
With the same genetic make up of patient = no rejection from the patients immune system
Can differentiate into any cell type
Uses of therapeutic cloning
Treating paralysis
Type 1 diabetes
Clinical problems with using stem cell medication
Mutations observed in cultured stem cells, behave like cancer
Difficulty in storing embryonic stem cells
No guarantee it’s successful
Ethical issues using stem cell medication
Embryos may become viewed as a commodity and not treated with respect
At what stage can an embryo be considered a person?
Social issues using stem cells
Many studies about stem cells are by commercial clinics = not peer reviewed
Patients exploited as it’s expensive and not certain it will work
Cell cycle
Series of stages a cell goes through growing + dividing
Nucleus function
Enclose genetic material
Cytoplasm function
Where chemical reactions take place eg first stages of respiration
Cell membrane function
Controls what molecules leave and enter the cell
Mitochondria function
Where aerobic respiration takes place
Ribosomes function
Sites of protein synthesis
What do you need to use to see ribosomes and mitochondria?
Electron microscope
Because they are very small
What type of shape do plant cells have?
A regular one
Can’t easily change it like animal cells
Chloroplasts function
Contain chlorophyll (site of photosynthesis)
Cell wall function
Made of cellulose
To strengthen the cell so if receives too much water won’t burst
Vacuole function
Permanent, filled with cell sap
Helps give the plant shape
Chromosomes
In pairs of 23 in a normal animal cell
So 46 in total
What do chromosomes contain?
Many genes
What is the cell cycle?
We have so many cells so they must be able to divide = cell cycle
Stages of cell cycle
1) DNA synthesis = replicates chromosomes for 2 copies
Cell grows and copies other internal structures
2) mitosis = 1 set of chromosomes pulleys to each side of the cell. Nucleus divides
3) cytoplasm and cell membrane divide = 2 identical cells
Mitosis functions
Growth and development of multicellular organisms
Repair
Asexual reproduction (unicellular organisms)
