Topic 1 Biology : Cell biology

what’s a Eukaryotic cell

a cell that contains its genetic material in a nucleus

what’s a prokaryotic cell

a cell that does not have a nucleus. doesn’t contain its genetic material in a nucleus

What is the role of a nucleus

contains DNA, genetic material

where do prokaryotic cells contain their DNA

A single loop of DNA & Plasmids

micrometer size & standard form

1 millionth of a meter. 1×10^-6

nanometer size & standard from

1 billionth of a meter. 1×10^-9

what does 1 order of magnitude mean

10x

what are mitochondria

where aerobic respiration takes place

what are ribosomes

sites of protein synthesis

what is cytoplasm

where chemical reaction takes place

what is the cell membrane

controls the movement of substances in and out of the cell

shape of plant and animal cells

plant cells = regular shape

animal cells = irregular shape

what are chloroplasts

Contain chlorophyll and are the sites of photosynthesis

what is the cell wall

made from cellulose. Strengthens the cell

what is a permanent vacuole

Vacuole gives the plant cell its shape. filled with cell sap

How is a sperm cell specialised

• Long tail helps them swim to the Ovum

• They are streamlined to help with swimming

• Contrail lots of mitochondria which provides energy needed for swimming

• Contain enzymes that allow them to digest their way through the outer layer of the ovum

how is a nerve cell specialised

• Long, so they can conduct nerve impulses between different areas of the body

• dendrites allowing nerve cells to communicate with other nerve cells

• myelin speeds up nerve impulse transmission

how are muscle cells specialised

• contain protein fibres that slide over eachother to allow contraction

• lots of mitochondria to release energy for contraction

how are root hair cells specialised

• Root hairs increase surface area. rate fo osmosis is greater

• don’t contain chloroplasts

• thinner walls than other plants for a shorter diffusion distance

how are xylem cells specialised

• doesn’t contain any organelles allowing free passage of water

• walls contain lignin, providing support for the plant

• no end walls providing long hollow tube for water & dissolved minerals

how is a phloem cell specialised

• very few sub-cellular structures to help flow of materials

• contain companion cell that provides mitochondria to the phloem vessel cell

role of xylem and phloem

xylem = carry water and dissolved minerals from the roots to the leaves

phloem = carry dissolved sugars up and down the plant

problems with light microscopes

1. limited resolution

2. limited magnification

advantages of electron microscope

1. Greater resolution

2. Greater magnification

magnification equation

what is binary fission

one bacterial cell splitting into two bacterial cells

how often can bacteria carry out binary fission

once every 20 minutes

formula for bacterial division

2^n n = number of rounds of division

what happens in the first stage of mitosis

DNA replicates to form two copies of each chromosome

what happens in the second stage of mitosis

mitosis takes place.

One set of chromosome is pulled to each end of the cell. nucleus also divides

what happens in the final stage of mitosis

cytoplasm and cell membrane divide to form two identical cells

3 functions of mitosis

1. growth and development of multicellular organisms

2. when an organism repairs itself

3. during asexual reproduction

where can we find stem cells (what can they differentiate into)

• early stage embryos - any thor of cells

• in bone marrow - blood cells

describe a bone marrow transplant (for leukaemia)

• patients existing bone marrow is destroyed using radiation

• patient receives a transplant of bone marrow from a donor

• stem cells in bone marrow decide to form new bone marrow & blood cells

why do some people reject therapeutic cloning

ethical or religious objections

plant stem cell

meristems

what is diffusion

the spreading out of particles resulting in a movement of higher concentration to an area of lower concentration

what can affect the rate of diffusion

1. concentration gradient

2. temperature

3. surface area

what is osmosis

diffusion of water from a dilute solution to a concentrated solution though a partially permeable membrane

what happens if you place a plant cell in water

water moves into the cell by osmosis and cell will expand. this is called turgid

what happens if you place a plant cell in a concentrated solution

water moves out of the plant cell it will cause the plant to shrink. flaccid

what is active transport

moves substances against the concentration gradient. requires energy from respiration