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DNA- deoxyribonucleic acid, the hereditary material of life in a cell's nucleus
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genes- carries codes for traits
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trait- characteristic of an organism
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acquired trait- from your parents
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environmental trait- from the surrounding environment
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chromosomes contain genes which are made of DNA
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Genes are inherited from your parents. Each gene codes for 1 trait, and thousands of genes are on each chromosome. Chromosomes in humans are arranged into 23 homologous pairs
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DNA is a double helix, and consists of phosphate, deoxyribose sugar, and nitrogen bases. Phosphate and sugar make the backbone, and nitrogen bases are the rungs of the ladder.
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nucleotide- a phosphate paired with a nitrogen base and deoxyribose sugar
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histone- special proteins that prevent DNA from tangling
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nucleosome- DNA and histone packages which resemble beads
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telomere- protective end on eukaryotic cells that shortens every time DNA replicates
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PURINES
(single-ringed) |
PYRIMIDINES
(double-ringed) |
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Adenine to
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Thymine with 2 H-bonds
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Guanine to
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Cytosine with 3 H-bonds
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1. Crossing over in prophase I
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2. Independent assortment in metaphase I and II. The chromosomes line up randomly each time.
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non-disjunction- a mistake that occurs during anaphase I and II, when the chromosomes do not separate and gametes end up having the wrong number
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MITOSIS
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BOTH
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MEIOSIS
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- all daughter cells are somatic
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- both for the purpose of reproduction
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- all daughter cells are gametes
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- 2 similar cells are produced
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- both create daughter cells
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- 4 different cells are produced
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- 46 chromosomes
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- 23 chromosomes
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- DNA is not crossed over
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- DNA is crossed over
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MEIOSIS I
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MEIOSIS II
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Prophase I
centrioles move to opposite poles, homologous chromosomes become visible and form tetrads, crossing over occurs, genetic material is exchanged |
Prophase II
- centrioles move to opposite poles, chromosome pairs become visible, crossing over does NOT occur |
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Metaphase I
- tetrads line up along the equator of the cell (staying as a pair) |
Metaphase II
- each chromosome moves to the equator of the cell |
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Anaphase I
- homologous chromosomes are pulled apart creating whole paired chromosomes on each side |
Anaphase II
- each chromosome splits and moves to opposite poles, the chromatid is now considered the chromosome |
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Telophase I
- nuclear membrane reforms, cytokinesis occurs, creating 2 diploid cells, which contain 46 chromosomes and are genetically different |
Telophase II
- nuclear membrane reforms, cytokinesis occurs, creating 4 haploid cells called gametes |
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PROKARYOTES
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BOTH
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EUKARYOTES
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- no nucleus or organelles
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- both forms of life
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- nucleus and organelles
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- simple and primitive
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- complex cells
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- usually single-celled
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- can be multicellular
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zygote- cell created when egg and sperm unite
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karyotype- map of chromosomes organized into homologous pairs
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diploid- total # of chromosomes in an organism, somatic cells
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haploid- half the # of chromosomes in an organism, sex cells
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MITOSIS
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MEIOSIS
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1. Asexual Reproduction
- 1 parent with identical offspring |
1. Create Gametes
- creates egg/sperm or egg/pollen - 2 parents with genetically different offspring |
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2. Repair
- to fix damaged cells and replace old cells |
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3. Growth
- nuclear division, and depends on the size and growth of the organism |
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mutation- any change made to DNA
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1. Translocation
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- part of a chromosome breaks off and attaches itself to a different chromosome
- Translocation Down's |
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2. Deletion
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- part of a chromosome is deleted
- Prader Willi Syndromelearning disabilities, behavioural problems, obesity, short stature, etc. |
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3. Duplication
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- part of the chromosome is repeated
- cause of seizures |
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4. Inversion
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- genetic code is flipped
- linked to infertility problems |
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Trisomy 13, Patau Syndrome
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heart defects, brain and spinal cord abnormalities, extra fingers and toes, cleft lip, usu. die by 1 yr. old
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Trisomy 18, Edward Syndrome
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abnormally shaped head, clenched fists, heart defects, usu. die by 1 yr. old
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Trisomy 21, Down Syndrome
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mild disability, can still form relationships and interact in society
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Trisomy XXY, Klinefelter Syndrome
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infertile males, look childish, high pitched voice, learning disabilities
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
