topic 1 cell biology

sep-dec

cells definition

the basic building blocks of life

unicelular definition

organisms only made up of one cell e.g bacteria

multi celular definition

organisms made up of many cells e.g dog

cell membrane definition

surrounds the cell and controlls what substances enter and leave the cell

cytoplasm definition

where all the chemical reactions take place

mitochondria definition

breaks down glucose and oxygen and releases oxygen and releases energy, called respiration

nucleus definition

contains DNA in the form of chromosomes (which have genes on them) and control the activities of the cell

ribosones definitions

synthesizes proteins from amino acids

animal cell

no cell wall

why are thwew many mitochondria in a muscle cell

so the mitochondria makes energy for the muscles to move

define permenwnt vacuole

contains cell sap (a solution of sugars and salt)

define chloroplasts

contains chlorophyll (green pigment) whuch absorbs light for photosynthesis

define cell wall

strengthens the cell. Contains cellulouse

plant cell

whats in a bacterial cell

• cell wall

• cytoplasm

• ribosomes

• loop of DNA

• cell membrane

• plasmid

• capsule

• flagellum-helps propell

Bacterial cells do not have their genetic material in a nucleus

define eukaryotic cell

a cel that has a nucleus e.g aniaml, plant, fungle cell

define a prokaryotic cell

a cell that does NOT have a nucleus e.g bacteria

difference between prokayotic cells and eukaritoc cells ()

Pro cells have a single loop of DNA

Pro cells may have a capsule

Pro cells have plasmaids

Pro cells are smaller in size

Pro cells dont have a nucleus

Pro cells dont have chromoaomwa
Euk cells may have mitochondria, chloroplasta and other orgenells present

what chromosomes do females have

what chromosomes do males have

XX - female

XY- male

gene definition

a short section of DNA that codes for a specific protein determing a characteristic (e.g eye colour)

what do we need cells for (2)

-growth and development of multicellular organisms

-replacing

what are the 3 stages in the cell cycle

stage 1

growth

replicates DNA to from 2 copies of each chromosone

makes new subcellular structures

stage 2

mitosis = nucleus divides

stage 3

cell divides

cytokinesis

mitosis

stem cells definition

undifferented cells

what can stem cells do (2)

-divide repeatedly to produce lots more undifferented cell

-differentiate into any type of human cell

where are stem cells from

and what can they do (3)

embryos and the embryos will be destroyed after being used

divide rapidly

can be cloned

differentiate into any type of human cell

what conditions can be treated with stem cells (3)

paralysis

type 1 diabities

replaces blood cell damage

what are stem cells from plant meristems used to produce

used to produce new plant clones

pros and cons of stem cells (2,1)

pros

can be grown quickly/economically

used for research and farming

cons

concern that using embryonic stem cells to treat people might cause cancer

treating conditions are relatively slow, difficult and expensive

ethical,social, economical issues

How many cells are in an early embryo?

Two to three hundred

How are embryonic and adult stem cells different? (2)

• Embryonic stem cells are only found in embryos. They can differentiate into all the cell types that make a human.

• Adult stem cells are found in children and adults. They can only differentiate into a limited number of cell types.

where are stem cells found

meristems

function of red blood cell

to transport oxygen cells around the body

red blood cell

adaptions and how its good (3)

• it has a biconcave disc shape- to maximize its surface area so more oxygen can diffuse in and out of the cell

• has many mitochondria - to release energy so it can absorb mineral ions by active transport

• doesnt have a nucleus - so the cell can carry more haemoglobin to transport more oxygen to body cells

sperm cell

function

to reach the egg and fertilise it so the male DNA can combine with the female DNA

sperm cell

adaptations and how its good (4)

• has many mitochondria - to release energy so it can swim to the egg

• has a streamlined head - to help it swim to the egg

• carries enzymes in its head - to digest through the egg cell membrane to fertilise it

• it has a tail - to help it swim to the egg

palisade mesophyll cell

function

to absorb light energy to carry out photosynthesis

palisade mesophyll cell

adaptations and how there good (1)

• it contains many chloroplasts - to absorb light for photosynthesis

neuron (nerve cell)

function

to carry electrical signals from one part of the body to another

neuron (nerve cell)

adaptaions and why its good (1)

• it has many branched connections at its ends - to connect to other nerve cells and form a network throughout the body

root hair cell

function

to absorb water and mineral ions from the soil

root hair cell

adaptions and how its good (2)

• has a root hair extension - to increase its surface area so it can absorb more water and mineral ions

• has many mitochondria - to release energy so it can absorb mineral ions by active transport

mussel cell

function

to contract

muscle cell

adaptation and why its good (1)

• has many mitochondria - to release energy for muscle contraction

total magnification equation

total magnification = magnification x magnification of eye pieces

how to use a microscope to use a microscope to view onion cells (8)

1. put a thin epidermal sample of onion cells onto microscope slide

2. add iodine solution to the specimin to stain the starch granu/es

3. place slide on stage

4. once the slide is on stage, adjust mirror OR switch light on so light passes through slide

5. use lowest power (x4 objective lens) initially

6. use coarse focus knob initially to focus the image

7. adjust fine focussing knob to focus the image further until you get a clear image

8. change objective lens to x40 the 10x eyepiece and 40x objective lenses will give you a total magnification of x400

dont need condenser

metres (m)→ centimeters (cm) →milimeters (mm) → micro metres (µm) →nanometers (nm)

m—-x100—>cm—x10—>mm—x1000—>µm—x1000—>nm

image size formular

Image size= Actual size x Magnification

(I AM)

magnification define

how many times bigger the image is compared to the origional origonal object

resolution define

the ability to distinguish between two points. A higher resolution gives a sharper (less blurred image)

difference between light microscope and electron microscope (3,9)

light microscope

can be used on live specimens

uses light as its source of illuminating radiation

uses lenses to focus the source of illuminating radiation

electron microscope

has a higher resolving power

can only produce black and white images

more expensive to purchace and operate

uses electrons as its source of illuminating radiation

uses electromagnets to focus the source of illuminating radiation

can achieve higher magnification

specimen must be prepared so needs to be dead

can be used on small organelles within the cell e.g mitochondria

can be used to view thin sections of a specimen or 3D structure of cells/tissues

define diffuse

the particles spread out from an area of higher concentration to an area of lower concentration

what happens when moving down a concentration gradient

no extra supply of energy is needed to move the particles down their concnetration gradient

particles move as they have energy

what moves into the cells (2)

oxygen

nutrients (e.g glucose, AA, fatty acids)

what moves out of cells(4)

waste products

carbon dioxide

urea

lactic acid

when is diffusion faster (3)

when the diffusion is shorter

a higher temperatures because particles have more energy

a higher temp because particles have more energy

when there is a higher concentration gradient

difference between diffusion and active transport

`diffusion

particles moving down the concentration gradient

no energy needed

active transport

particles moving against the concentration gradient

energy if needed

what happens when plant root hair cells absorb the mineral ions in the soil

do they go with or against the concentration gradient

the plant root hair cells absorb the mineral ions in the soil. The plant root hair cells absorb the higher concentration of minerals which uses energy which is in the repiration so they go against concentration gradient

define diffusion

e.g of types of substances that move this way

diagram

when particles move from high concentration to low concentration down the concentration gradient

a prosses by which substances move down their concentration gradient from a region ofhigh concentration gradient to a region of lower concentration. Is a passive prosses (no energy required) (kind of like water moving down a hill)

all ways takes place

glucose

active transport definisition

diagram to represent this

e.g of types of substances that move this way

the movement of molecules across a cell membrane, from a region of lower concentration to a region of higher concentrationand requiring energyfrom cellular respiration

carbon dioxide

dilute solutions

concentrated solutions

contain a high concentration of water molecules

contain a lower concentration of water molecules

definne osmosis

osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permable membrane

if we place a plant cell into a concentrated solution then would the cell shrink or expand

the water would move out of the plant cell by osmosis so it would shrink

if we place a plant cell in water then would the plant cell shrink or expand

the water will move into the cell by osmosis so the plant cell will expand

osmosis practicle (9)

1. peel the potato as the potato skin can affect osmosis

2. use a cork borer so each cylinder has the same diameter to produce 3 cylinders of potato

3. use a scalpel to trim each cyliner of potato so each cylinder is the same hight (3cm as a shorter cylinder then we mght not be able to measure the affect of osmosis)

4. measure length of each cyl with ruler and mass with a balance

5. place each cylinder into a test tube. Add 10cm³of a 0.5 molar sugar solution to the first test tube

6. add 10cm³of 0.25 sugar solution to the second test tube and 10cm³of distilled water to the third test tube (distilled not tap as distilled contains no dissolved substances which could affect the rate pf osmosis)

7. leave overnight to allow for osmosis to take place

8. remove potato cyl and gently roll on paper towl (dont press as we only want to remove surface water not force water out of cell)#

9. measure length and mass of cyli again and calcultae % change of length and mass (% change = change in value/ og value x 100) and plot a graph

what would a positive % change mean for the potato cylinder

negative

gained mass

lost mass

rp osmosis in plant tissues

independent variable(1)

dependent variable(1)

control variable (4)

I - concentration of sugar solution
D - percentage change in mass
C - size of potato cylinder

-type of plant tissue

-surface area of potato cylinder

-temperature

how could the osmosis investigation more reliable

repeat / use more potato chips in each solution

plasmolysed meaning

a plant cell losing water content and therefore contracting and shrinking its cytoplasm and plasma membrane away from the inside of its cell wall

turgid meaning

a plant cell that has been filled with water as a result of osmosis

flaccid meaning

cell that lacks turgidity, i.e. it is not swollen and plump, but loose or floppy and the cell has become drawn in and pulled away from the cell wall

alveoli

air sacks in lungs

gases exchange occurs here

millions of alveoli- large surface area- increased exchange

diffusion of O2 and CO2

small intestines →villi

one cell thick →(short diffusion distance)

micro villi on each cell = increased surface area

good blood supply - high concentration gradient and diffusion

mitochondria for active transport

diffusion also happens