vault backup: 2026-10-21 10:11:52

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+[[G11 Pre-AP Biology]]
+Human body cells have 46 chromosomes.
+
+Chromosome 23 is a sex chromosomes.
+First 22 chromosomes are autosomes.
+
+First chromatid of first pair is taken in metaphase, organised picture of chromosomes.
+
+DNA is the molecule that holds information.
+Chromosomes are structures that consist of DNA and associated proteins.
+
+DNA wraps around histones and forms nucleosomes.
+Nucleotide has 1 phosphate, base, and deoxyribose sugar.
+
+4 different bases.
+Adenine compliments thymine.
+Cytosine compliments guanine.
+
+Genes are sections of DNA that instructs cells to make proteins.
+Chromosomes are chromatins but more curly to be more condense and sturdy.
+
+Sperm and egg should have 23 chromosomes, zygote (fertilized egg) should have 46.
+
+Interphase is when all cell functions occur, DNA replicates, and the cell goes through G1, synthesis, and G2.
+Prophase is when chromatin condenses, nuclear membrane disappears, centrioles move, and spindle fibers form.
+Metaphase is when spindle fibers pull double stranded chromosomes to center of cells.
+Anaphase is when spindle fibers contract and pull sister chromatids apart. Single stranded chomosomes start migrating to opposite sides.
+Telophase is when single stranded chromosomes arrive at opposite sides, nuclear membrane and nucleolus reappear, and spindle fibers disappear.
+Cytokinesis is when cell splits into 2 identical daughter cells.
+
+Homologous chromosomes have the same gene but aren't identical. Same length, centromere location, and banding pattern. One from each parent.
+
+Allele are different version of a gene.
+
+Haploids (n) are one set of chromosomes.
+Diploids (2n) are two sets of chromosomes.
+One set from sperm, one from egg.
+Humans have 46 chromosomes, 23 chromosomes per set.
+
+Meiosis is the process of producing cells with half the number chromosomes of parent cells. Increases genetic variation, different combinations of alleles.
+
+Process of meiosis:
+Interphase involves growth of cell and replication of chromosomes.
+
+Prophase I.
+Synapsis is when the homologous chromosomes pair up.
+Crossover occurs. Non sister chromatids exchange information (homologous chromosome).
+Centrosomes move to opposite sides, spindle forms (nuclear membrane disappears, chromosomes coil).
+Tetrad is a pair of homologous chromosomes/bivalent.
+
+Metaphase I.
+Homologous pairs (tetrad) line up along equator of cells.
+![[Pasted image 20261013105105.png|496]]
+Cross over has already occured in prophase I.
+In mitosis they aren't lined up accross from their pair.
+Spindle fibers attach to centromeres of each homologous chromosome.
+
+Anaphase I.
+Homologous chromosomes separate from each other, homologues of each bivalent separate. Sister chromatids are still attached unlike mitosis.
+Double stranded chromosomes start moving to opposite sides.
+
+Telephase I.
+Double stranded chromosomes arrive at opposite ends.
+Spindle fibers disappear.
+Chromosomes uncoil.
+Nuclear membrane reforms.
+
+Meiosis part 2 is just like mitosis.
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+[[G11 Pre-AP Biology]]
+Traits are genetic characteristics.
+Alleles are alternate forms of a gene.
+Genotypes are the genetic make up of an organism.
+Phenotypes are traits that get expresssed.
+Homozyhous are 2 identical alleles of a gene.
+Heterozygous are 2 different alleles of a gene.
+
+Gregor Mendel crossed 2 pea plants, of which were green and yellow, and expected the result to be greenish yellow. The resultings peas were yellow. He concluded that there is no blending effect. 
+
+Gregor Mendel then crossed the yellows with the yellows, and the resulting was 6000 yellows and 2000 greens. The conclusion is that even if one train disappeared in F1 generation, it may reappear. Therefore there must bee 2 factors for each trait. These factors must segregate during meiosis.
+
+Dominance is a trait that always appears, example being brown hair.
+Recessive is a trait that only appears if both alleles of this trait is inherited.
+
+Mendel's laws:
+* Law of segregation: Each organism has 2 factors for each trait (2 alleles). During meiosis, each factor must separate.
+* Law of independent assortment: Inheritance of 1 trait foes not influence the inheritance of another.
+Punnet square, used to predict possible genotypes and phenotypic possibilities.
+Requires let statment, P, and gametes, tic tac toe board, genotypes and phenotypes.
+
+Example begin:
+Monohybrid cross:
+
+Must use uppercase for dominant and lowercase for recessive.
+Let statement:
+1 trait = abilitiy to taste.
+Let T rep better tasting allele.
+Let t rep no bitter tasting allele.
+
+P1 genotype:
+    <u>TT</u>                   x           <u>tt</u>
+homozygous taste    cannot taste
+
+Gametes:
+F1 (filial I generation)
+![[Pasted image 20261019112113.png|391]]
+<u>Genotypes</u>:
+100% Tt
+
+<u>Phenotypes</u>:
+100% can taste bitterness.
+
+AFTER INCESTING TWO OF THESE
+
+$P_2$: Tt x Tt
+
+![[Pasted image 20261019112757.png]] <u>Genotypes</u>:
+25% TT
+50% Tt
+25% tt
+
+<u>Phenotypes</u>:
+75% can taste bitterness.
+25% can't taste bitterness.
+
+
+Example concluded.
+
+Autosomal traits are any traits found on chromosome 1-22.
+Carriers are people having a recessive allele.
+Sex linked traits are any traits found on sex chromosomes.
+X+Y are not homologous.
+X-linked means it's found on X chromosome.
+Y-linked means it's found on Y chromosome.
+
+Colorblindness is recessive and found on X chromosome.
+Hemophilia is the inability to clot blood and is found on the X chromosome.
+Hairy ears is a Y-linked.
+
+Example begin:
+Let:
+$X^h$= hemophilia allele
+$X^H$= no hemophilia
+$Y$= represents Y allele
+
+$P_1$:$X^HX^h$ x $X^HY$mop
+gametes: ($X^H$) ($X^h$) x -($X^h$) -($Y$)
+
+|         | -($X^h$) | -($Y$) |
+| ------- | -------- | ------ |
+| ($X^H$) | $X^HX^H$ | $X^HY$ |
+| ($X^h$) | $X^HX^h$ | $X^hY$ |
+Genotypes:
+25% $X^HX^H$
+25% $X^HX^h$
+25% $X^HY$
+25% $X^hY$
+
+Phenotype:
+50% female + no hemophilia
+0% female + hemophilia
+25% male + no hemophilia 
+25% male + hemophilia
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+[[G11 Pre-AP Biology]]
+Mutation is any change to DNA in a cell.
+If a mutation occurs in a germ cell, it well get passed on to the next generation.
+Mutations aren't necessarily a detriment, it can also be beneficial or have no effect (silent mutations).
+
+Four main types of chromosome changes are:
+- Deletion, where a segment is deleted from the chromosome.
+- Translocation, which is crossover between non homologous chromosomes
+- Inversion, where a section is inverted 180 degrees.
+- Duplication, where a section is repeated.
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+[[G11 Pre-AP Biology]]
+
+Incomplete dominance is when neither allele is dominant, therefore a heterozygous will have intermediate phenotypes between that of its homozygous parents.
+
+Example being two flours homozygous red flowers and homozygous white flowers producing pink flowers.
+If you then breed these pink flowers together, there's 25% chance of red flowers, 25% chance for white flowers and 50% chance of pink flowers.
+
+Co dominance is when both alleles are dominant. Therefore a heterozygous will have both alleles fully expressed.
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+[[G11 Pre-AP Biology]]
+![[Pasted image 20261015104528.png]]
+![[Pasted image 20261015104509.png]]Non-disjunction is the failure of chromosomes seperating.
+Aneuploidy is when the number of chromosomes is incorrect.
+Trisomy is an extra chromosome.
+Monosomy is missing chromosomes.
+Polyploidy are extra set(s) of chromosomes.
+Triploidy is 3 sets of chromosomes (3n).
+Tetraploidy is 4 sets of chromosomes (4n).
+Octaploidy is 8 sets of chromosomes (8n).
+
+Trisomy 21 is Down's syndrome.
+Trisomy 18 is Edward's syndrome.
+Trisomy 13 is Patau's syndrome.
+47 XXY is Klinefelter's syndrome.
+47 XYY is Jacob's syndrome.