Genetics - Callum

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Genetics - Callum by Mind Map: Genetics - Callum

1. Genetic Terminology

1.1. Genotype

1.1.1. The alleles that code for a trait homozygous A genotype made up of two of the same alleles heterozygous A genotype made up of two different alleles

1.2. phenotype

1.2.1. How a trait appears Recessive The allele that is masked in the presence of another Recessive The allele that is masked in the presence of another

1.3. alleles

1.3.1. Variations of a trait

1.4. Gene

1.4.1. This is a section of DNA that codes for a particular trait

1.5. hybrid

1.5.1. Another term for heterozygous

1.6. Purebreed

1.6.1. Another term for homozygous

2. DNA & RNA

2.1. DNA

2.1.1. Your DNA contains enough information as 1000, 500 page text books worth of information. Your DNA is 99.9% similar to the person next to you 50% similar to a banana. 90% similar to a mouse, you are made of 75 trillion cells containing 3 billion base pairs.

2.1.2. living things depend on proteins called enzymes.

2.1.3. All living things contain proteins

2.1.4. DNA determines the structure of proteins. and all the actions of

2.1.5. DNA Structure A molecule of DNA is made up of millions of tiny subunits called Nucleotides. Each nucleotide consists of: 1. Phosphate group 2. Pentose sugar 3. Nitrogenous base DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix. A molecule of DNA is made up of millions of tiny subunits called Nucleotides.

2.1.6. DNA and genes A gene is a section of DNA that codes for a protein. Base Pairs

2.1.7. DNA Replication ALL organisms undergo DNA replication first makes a copy of its chromosomes through DNA replication Each cell in body has copy of DNA that was present in the original fertilized egg ALL organisms undergo DNA replication

2.1.8. From DNA to Protein Sequencing of nucleotides in DNA contain information - through proteins Proteins fold into complex 3-D shapes and become key regulators DNA does not leave the nucleus.

2.2. RNA

2.2.1. RNA Structure RNA differs from DNA in 3 ways: Single stranded vs. double stranded Ribose sugar vs. deoxyribose Contains URACIL(U) vs. of thymine (T)

2.2.2. Translation to Proteins mRNA leaves the nucleus with the code for the protein Remember CODONS? (the sets of 3 that DNA is arranged in) These code for Amino acids There are 20 possible combinations and as a result 20 amino acids There are also STOP codons and START codons Nucleotide sequence transcribed from DNA to mRNA is the genetic message. The complete info for life. 20 AA act like the alphabet for DNA (26 letters make millions of words.) 64 possible combinations of the 20 AA. Similar to a computer binary code 001100101000111110


3.1. Mitosis

3.1.1. when a parent cell divides to produce two identical daughter cells

3.1.2. process of dividing the nuclear material

3.1.3. Stages of Mitosis Stage one:Prophase Centrioles move to opposite poles of the cell Chromatin condenses and shortens into chromosomes Spindle fibres form between the centrioles Nuclear membranes starts to disappear Stage 2:Metaphase Spindle fibres attached to centromeres pull chromosomes into place Chromosomes line up across the equator of the cell Centrioles duplicate Stage 3:Anaphase Chromatids separate at the centromere Single-stranded chromosomes are pulled to opposite poles by spindle fibres contracting Stage 4:Telophase Two nuclear envelopes form Single-stranded chromosomes uncoil to become chromatin Cytokinesis occurs after telophase: Organelles distributed between the two daughter cells & the cell membrane pinches inward

3.2. Meiosis

3.2.1. Sexual reproduction any reproduction that involves meiosis requires more energy & time than asexual reproduction better able to adapt to changing environments - differences between individuals genetic information from parent cells are combined

3.2.2. Asexual reproduction Asexual reproduction is any reproduction that does involve meiosis

3.2.3. Somatic Cells and Gametes Somatic Cells Somatic Cells are “body” cells and . contain normal number of chromosomes ….called the “Diploid” number (the symbol is 2n) Gametes “sex” cells Male Gamete is Sperm Female Gamete is the Ovum (ova = pl.)

3.2.4. Fertilization Ovum + Sperm = Fertilization Ovulation the ovum is released from the ovary Fertilization, in humans, occurs in Fallopian tube. Fertilization results in formation of Zygote (fertilized egg)

3.2.5. Chromosomes DIPLOID Diploid number (2n) it has two matching homologues per set. Most organisms are diploid. Humans have 23 sets of chromosomes Homologous Chromosomes Pair of chromosomes (maternal and paternal) that are similar in shape and size. 22 pairs of autosomes 1 pair of sex chromosomes Homologous pairs (tetrads) carry genes controlling the same inherited traits. Each locus (position of a gene) is in the same position on homologues. Humans have 23 pairs of homologous chromosomes.

3.2.6. Stages of Meiosis Cell division that reduces the chromosome number by one-half Phases: ****Interphase a. prophase I b. metaphase I c. anaphase I d. telophase I Phases: ******Interkinesis a. prophase II b. metaphase II c. anaphase II d. telophase II & cytokinesis

3.3. Meiosis vs Mitosis

3.3.1. MEIOSIS to produce gametes (sex cells) which unite during sexual reproduction the number of chromosomes in each sex cell is half of parent cell

3.3.2. MITOSIS to maintain genetic continuity the number of chromosomes in each daughter cell stays the same



5.1. Monohybrid Crosses

5.1.1. cross between two organisms with different variations at one genetic chromosome of interest.

5.1.2. governed by two or multiple variations for a single locus

5.2. Incomplete Dominance

5.2.1. neither allelle is completely dominant

5.2.2. more than 2 phenotypes can occur

5.2.3. Result = Heterozygous phenotype somewhere in between homozygous phenotype.

5.3. Dihybrid Cross

5.4. Codominance

5.4.1. a cross between organisms with two different phenotypes

5.4.2. neither allele are dominant; both are expressed.

5.4.3. produces offspring with has both phenotypes of the parental traits shown.