B5 Growth and Development

Mind Map by , created over 6 years ago

Biology Mind Map on B5 Growth and Development, created by theflyingduck on 04/28/2013.

Created by theflyingduck over 6 years ago
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B5 Growth and Development
1 The Development of Organisms
1.1 Development of New Organisms
1.1.1 Up to the 8 cell stage, all human cells are unspecialised and they can have any gene switched on to form any kind of specialised cell. After the 8 cell stage the cells in an embryo become specialised and form differernt types of tissue The cells contain the same genes, but many genes are not active (switched off) because the cell only produces the proteins it needs to do its job.
1.2 Living organisms are made up of cells. In multicellular organisms such as humans and plants.
1.2.1 Similar cells from a tissue, groups of tissues form an organ, groups of organs make up systems within the whole organism.
2 Mitosis
2.1 This is the division of body cells to produce new cells.
2.1.1 Each new cell has; Identical sets of chromosomes as the parent cell. The same number of chromosomes as the parent cell The same genes as the parent cell
2.2 For growth, for repair, to replace old tissues
2.3 To enable mitosis to take place, cells go through a cycle of growth and then division. The cycle repeats itself until the cell can no linger divide.
2.3.1 When a cell enters the growth phase. The number of organelles increase, the chromosomes are copied- the two strands of each DNA molecule seperate and new strands form alongside them.
2.3.2 When a cell enters the division phase of the cycle. The copies of the chromosomes separate, the cell divides
3 Meiosis
3.1 Meiosis only takes place in the testes and ovaries and is a special type of cell division that produces gametes (sex cells,e.g egg and sperm).
4 Fertilisation
4.1 During fertilisation a male gamete (sperm) and a female gamete (egg) fuse together to produce a single body, cell called a zygote
4.1.1 The zygote then divides by mitosis to produce a cluster of cells called an embryo. The embryo continues to divide by mitosis, after which the cells become specialised, until birth as a fully developed babyb
5 Variation
5.1 Meiosis and sexual reproduction produce variation between offspring and parents
5.1.1 When the gametes fuse, genetic information from two individuals is combined.
5.1.2 For each gene, just one of each parent's alleles is passed on.
5.1.3 Each offspring have a different combination of alleles from either parent.
5.1.4 The offspring can have different characteristics from each other.
6 Genes
6.1 Genes are present in the chromosomes in each cell nucleus.
6.1.1 The control Growth and development in organisms The development of characteristics, e.g. eye colour.
6.2 Genetic code
6.2.1 Genes control characteristics by providing intructions for the production of proteins The instructions are in the form of a code, made up of four bases that hold the two strands of the double helix of the DNA molecule together. The four bases always pair up in the same way. Adenine (A) pairs with Thymine (T) Cytosine (C) pairs with Guanine (G)
7 Controlling Growth and Development
7.1 DNA is too large to leave the nucleus. The genes therefore stay inside the nucleus but the production of proteins takes place outside the nucleus.
7.1.1 Information stored in the genes has to be transferred into the cytoplasm.The transfer is done in the following way. 1). The relevant section of DNA is unzipped. 2).Instructions are copied onto smaller molecules(messenger RNA or mRNA) 3). These molecules leave the nucleus and carry the instructions to the ribosomes 4). The ribosomes follow the instructions to make a relevant protein.
7.2 The sequence of bases in a gene determines the order in which amino acids are joined together to make a particular protein.
7.2.1 A group of three base pairs codes for one amino acid in a protein chain, called a triplet code. There are are 20 different amino acids are made. The structure of the protein depends on the amino acids that make it up, the process is as follows: 1).DNA unravels at the correct gene. 2). A copy of the coding strand is made to produce mRNA 3). The mRNA copy moves from the nucleus into the cytoplasm. 4). The triplet code is decoded by the ribosomes. 5).Amino acids are joined together to form a polypeptide (protein)
8 Stem cells
8.1 stem cells could be used to.
8.1.1 help treat diseases and disorders.
8.1.2 Repair damage to various tissues
8.2 There are three sources
8.2.1 Embryos Only embryonic stem cells are completely unspecialised and can be used to form any cell type Ethical decisions need to be taken when using embryonic stem cells and this work is subject to government regulation.
8.2.2 Blood from the umbilical cord
8.2.3 Adult stem cells from bone marrow
9 Differentiation in Plants
9.1 Plant cells divide by the process of mitosis, New cells in plants specialise into the cells of: roots, leaves, flowers
10 Meristems
10.1 plant growth only occurs in areas called meristems, which are sites where unspecialised cells are dividing by mitosid
10.1.1 The two types of meristem: Lateral, which leads to increased girth and Apical which leads to increased height and longer roots some plant cells remain unspecialised and can develop into any kind of plant cell. these cells allow clones of plants with desireble features
11 Xylem and Phloem
11.1 Xylem tubes are used by the plant to: transport water and soluble mineral salts from the roots to the stem and leaves.
11.2 Phloem tubes are used by the plant to transport dissolved food to the whole plant for respiration or storage.
12 Cuttings
12.1 Produced in the following way.
12.1.1 1). Cuttings are taken from a plant. 2). the cuttings are put in a rooting hormone. 3).roots start to form and the new plants develop.
13 Photopism
13.1 Plants respond to light by changing the direction in which they grow. This is called phototropism.They grow towards a light source.
13.1.1 Auxin is produced at the shoot tip, it moves down the shoot, causing cells further down the shoot to grow When light shines on a shoot, auxin near the light source is slowly destroyed, so there's more auxin on the far side away from the light. Making the plant bend towards the light.

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