TOPIC B1- CELL BIOLOGY Flashcards
organisms can be what
-prokaryotes
-eukaryotes
explain what eukaryotic cells are
-complex and include all animal and plant cells
-eukaryotes are organisms made up of eukaryotic cells
explain what prokaryotic cells are
-smaller and simpler e.g bacteria
what is a nucleus
contains genetic material that controls the activities of the cell
what is a cytoplasm
a gel-like substance where most chemical reactions happen
-it contains enzymes that control the reactions
what is a cell membrane
holds the cell together and controls what goes in and out
what is a mitochondira
where most reactions for aerobic respiration take place
what is a ribosome
where proteins are made
state what is found in an animal cell
-nucleus
-cytoplasm
-cell membrane
-mitochondira
-ribosome
what is a rigid cell wall
-made of cellulose
-supports the cell and strengthens it
what is a permanent vacuole
contains a cell sap, a weak solution of sugar and salts
what is chloroplasts
where photosynthesis occurs, they contain a green substance called chlorophyll, which absorbs light
what is different about plant cells to animal cells
they also contain
-a rigid cell wall
-permanent vacuoles
-chloroplasts
bacteria are …
prokaryotes
state what is found in a bacterial cell
-cell membrane
-cytoplasm
-cell wall
-a singular strand of DNA that floats freely in the cytoplasm
-plasmids
state what light electrons use
-light and lenses to form an image of a specimen and magnify it
-let us see individual cells and large subcellular structures, like nuclei
state what electron microscopes use
-electrons instead of light to form an image
-have a higher magnification
-higher resolution to light microscopes
explain why electron microscopes are better than light ones
-they let us see much smaller things in more detail e.g mitochonria
-higher resolution
-higher magnification
formula for magnification
magnification= image size
real size
resolution definiton
the ability to distinguish between 2 points
differentiation meaning + when does it happen most
the process where a cell changes to become specialised for its job
-as organisms develop
state 5 specialised cells
-sperm cells
-nerve cells
-muscle cells
-root hair cells
-phloem and xylem cells
state what sperm cells do
-specialised for reproduction
-**function **is to get male DNA to female DNA.
-has a long tail and streamlined head to help it swim to the egg
-lots of mitochondria in the cell to provide energy
nerve cells
specialised for** rapid signalling**
-carries electrical signals from one part of the body to the other
-cells are long and have branched connections at their ends to connect other nerve cells and form networks
muscle cells
specialised for contraction
-cells are long, so they have space to contract
-contain lots of mitochondria to generate energy
root hair cells
specialised for absorbing water and minerals
-long hairs that stick out into the soil
-big surface area for absorbing water and mineral ions from the soil
phloem and xylem
specialised for **transporting substances **
-they form phloem and xylem tubes that transport food and water around plants
-cells are long and joined end to end
-xylem cells are hollow in the centre
-phloem have very few subcellular structures so stuff can flow through
what are chromosomes?
-they contain genetic infomation
-coiled up lengths of DNA molecules
why does the cell cycle make new cells
for
-growth
-development
-repair
what is mitosis
the stage of a cell cycle when the cell divides
-multicellular organisms use mitosis to grow or replace cells that have been damaged
what are the 2 main stages of the cell cycle
-growth & DNA replication
-mitosis
explain dna replication
-before dividing the cell has to grow and increase the amount of subcellular structures e.g mitochondria and ribosomes
explain the cell cycle mitosis
-1ST stage of cell cycle
—— DNA condenses to form 2 copies of each chromosome.
-chromosomes line up along the centre of the cell
-cell fibres pull 2 arms of each chromosome to opposite sides of the cell
-THEN membranes form
-then nucleus has divided
-cytoplasm and nucleus then divide
cell has now produced 2 daughter cells
CYTOKINESIS- entire cell divides to form 2 identical daughter cells
what are undifferentiated cells called and their significance
-stem cells that can divide to produced lots more undifferentiated cells
-found in human embryos
how can embryonic stem cells be used to cure diseases
-they replace faulty cells in sick people and make insolin-producing cells for people with diabetes and nerve cells for people paralysed
state why some people are against stem cell research
-they feel human embryos shouldn’t be used for experiments, as each is a potential human life
-some embryos used are unwanted ones from fertility clinics
state what stem cells can do
-produce clones
-can be used to grow more plants of rare species
-produce identical plants
define diffusion
the spreading out of particles from an area of higher concentration to an area of lower concentration
state 3 ways that makes diffusion happen quicker
-bigger concentration gradient
-higher temperatures
-greater the surface area
state what molecules can diffuse through cell membranes
-oxygen
-glucose
-amino acids
-water
define osmosis
the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
osomosis is a
type of diffusion
what type of molecules move by osmosis
water
active transport
-movement of particles against a concentration gradient, from an area of lower concentration to an area of higher concentration using energy transferred during respiration
root hairs
-each branch of a root will be covered in millions of microscopic hairs
-gives the plant a large surface area for absorbing water and mineral ions from soil
-plants need these for healthy growth
active transport needs energy from what
respiration
cells use diffusion to take in substances they need and get rid of waste products
-oxygen + carbon dioxide are transferred between cells and the environment during gas exchange
-in humans urea diffuses from cells into the blood plasma
how are exchange surfaces adapted to maximise effectiveness
-thin membrane, so substances have short distances to diffuse
-large surface area so lots of substances can diffuse at once
-exchange surfaces in animals have lots of blood vessels
where does gas exchange happen
in the lungs
-the job of lungs is to transfer oxygen to the blood and to remove waste carbon dioxide from it
-lungs contain millions of air sacs called alveoli where gas exchange happens
how are alveoili adpated
-enormous surface area
-moist lining for dissolving gases
-thin walls
-good blood supply
to maximise the diffusiom of O2 AND CO2
importance of the villi
-inside a small intestine
-increase surface area in a big way so digested food is absorbed quicker into blood
-they have a single layer of surface cells
-good blood supply to assist quick absorption
explain how the structure of leaves let gases diffuse in and out of cells
-underneath of leaf is an exchange surface, and is covered in stomata
-oxygen and water vapour also diffuse out through the stomata
-walls of cells inside the leaf form more exchange surfaces
-air spaces increase the area
how do gills have a large surface area for gas exchnage
-gill filaments, that give a big surface area for exchange of gases
-covered in lamellae, increasing the surface area
-thin surface layer of cells to minimise distance that gases need to diffuse
