Biology year 9 cell division

In which part of the cell is DNA found?

Nucleus

Order these structures into order from largest to smallest?

- cell, nucleus, chromosomes, gene, deoxyribonucleic acid DNA

Largest

- cell

- nucelus

- chromosomes

- gene

- DNA

Where do our DNA and genes come from?

Our parents

What is inside the nucelus?

Chromosomes

How many pairs of chromosomes do human cells have

23 pairs

What are chromosomes made up of?

long strings of DNA

What is the shape of DNA ?

Double helix

What is a section of DNA called

Gene

What is build from the gene when it ti " read" ?

Protein

What determines the proteins that is made?

The gene

What does the nucleus control

the nucelus controls all the clls activities and contains genetic information

How is genetic information saved

In the form of chromosomes. The human nucleus contains 23 pairs of chromosomes ( 46 chromoesomes)

How are the arms of chromosomes formed.

Long moleculues of DNA coil up to form the arms of the chromosomes

What do chromosomes carry.

Chromosomes carry genes. Genes are short lengths of DNA containing instructions to put amino acids together in particular oder to make proteins.

What is DNA made up of

DNA is made up of bases which form the protein code for the gene. Dna has a double helix structure

What do genes do?

A gene contains the instructions needed to code for the correct order of amino acids to make a specific protein

What are non identical pairs of chromosomes have the same type of gene?

A homologous pair of chromosomes.

What is a gene

a section of DNA that contains information that control specific characteristics

What is an alleles?

one of two or more versions of DNA sequences ( a single base or a segment of bases) at a given genomic location

What does DNA stand for?

deoxyribonucleic acid

what are chromosomes made up of?

Long molecules of DNA

Describe the structure of a DNA molecule

double helix structure

How does the gene help to make a specific protein?

By telling the cell what order to put the amino acids in

What structure and components are made of proteins in our bodies?

Enzymes, collagen, antibodies, haemoglobin, muscle fibres.

What are the 2 types of cell divisoin

Mitosis & meiosis

What type of cell does mitosis make?

Makes identical copies of cells - 24 pairs of chromosomes in parent and daughter cells.

In what type of cells does mitosis replication take place?

Every cell in the body- except the sex cells ( gametes)

What type of cells do meiosis produce?

Produces cells with half the number of chromosomes compared to the parent cell.

In which cell does meiosis replication take place.

Only makes gametes - sperm/ egg cell.

What is Mitosis?

Mitosis is when a cell divides and splits to form two genetically identical daughter cells.

Mitosis is a type of cell division

The cell cycle - series of stages of cell division

Stage 1 - longest stage

Cells increase its subcellular structures such as ribosomes and mitochondria.

The parent cell duplicates its DNA. This is when the x-shaped chromosomes are formed.

Stage 2 - Mitosis

The chromosomes line up at the centre of the cell

Cell fibres pull each arm/set of the chromosome to each of the cell.

Stage 3 - splitting

The cell membrane and cytoplasm splits into two daughter cells.

What is Mitosis used for?

1. growth

2. to replace damaged cells or repair damaged tissue

3. In asexual reproduction ( this is where one parent can produce offsprings)

Where does mitosis happen in biology?

Fertilisation - when the male and female gametes meet and nuclei fuse.

What is Meiosis

Meiosis is a form of sexual reproduction. Meiosis produces cells which have half the normal number of chromosomes. The process requires two cell divisions.

Meiosis occurs in the reproductive organs ( ovaries and testes) and produces gametes ( sex cells ). In females the gamete is called the egg cell and in males the sperm cell.

Where does mitosis and meiosis occur?

Mitosis - in the body cells

Meiosis - in cells in the reproductive organs only

What type of cells are produced in Mitosis and Meiosis?

Mitosis - Body cells

Meiosis - Gametes

How many cell divisions take place in Mitosis and Meiosis?

Mitosis - one

Meiosis - two

How many new cells are produced in Mitosis and Meiosis?

Mitosis - two

Meiosis - four

How many sets of chromosomes do the new cells have in Mitosis and Meiosis?

Mitosis - two

Meiosis - one

What are stem cells?

Stem cells are undifferentiated cells that are able to differentiate into specialised cell types.

Where can adult stem cells be located?

- bone marrow

- skin

- brain

- eye

They can also be extracted from embryos.

Where do we find stem cells?

Stem cells can be found in early human embryos and in some adult stem tissues such as bone marrow.

What are the advantages and disadvantages of using embryonic stem cells?

Advantages: easier to grow, can differentiate into many more cells types, can treat lots of diseases, lots of avaliable, better to use them than waste them.

Disadvantages

- Harder to obtain, ethical considerations e.g. destroying embryo, cannot get permisson from embryos.

What are the advantages and disadvantages of using adult stem cells?

Advantages

Easier to obtain, can get permisson from patient, no ethical issue, safe and well-tested

Disadvantages

- harder to grow, develop into limited cell types, can be painful to obtain e.g. from surgery, so may get less doners.

Why might scientists use stem cells?

They could be used to replace cells that are dead or damages e.g. Alzheimer's or diabetes. This is known as therapeutic cloning.

What diseases can stem cells cure?

Diabetes, spinal cord injuries, heart damage after an attack, eye conditions.

What would be the advantage of using a patient's own stem cells to treat themselves?

The stem cells would contain the same genes and so would not be rejected by their body

Embryonic stem cells compared to Adult stem cells.

Embryonic

- Can be collected earlu

Destroys embryos

- Can differentiate in large number of cells.

Adult

- Simple operation to collect

Only differentiate into small number of cells.

Both

Cure disease

Where are stem cells found in plants?

Meristems of plants

Uses of stem cells in plants

- Disease resistant

- prevent rare species going extinct

- cheap, quick production of food.

What is the future for stem cells?

Scientists have found embryonic stem cells in the unbilical cord blood of new born babies

- stem cells have also been found in the amniotic fluid surrounding the baby as ti grows

- using these instead of cells from spare embryos should help to overcome some ethical concerns about stem cells.