AP Bio Unit 5 flashcards (Hereditary)

Meiosis ensures ______

formation of haploid gametes cells in s3xually reproducing diploid organisms 

Diploid cells

2 full sets of pairs of chromosomes. 2n (body cells are diploid)

Haploid

1 set of chromosomes. N (s3x cells)

Later, two haploid gametes come together in s3xual reproduction to make a diploid cell

Result of Meosis

4 haploid daughter cells with half the number of chromosomes as the parent cell 

Process of Meiosis l

• Prophase 1: 

  • Nuclear envelope disappears, fibers form, DNA coils into double chromosomes made of sister chromatids. Double chromosomes pair up. 

  • Crossing over: chromatids exchange genetic info 

• Metaphase I: 

  • Align across the center of the cell in pairs 

• Anaphase I: 

  • Fibers separate chromosome pairs. Double chromosomes migrate to opposite ends of the cell.

•  Telophase I: 

  • Nuclear envelope reappears and establishes 2 nuclei. Daughter cells are haploid now 

Process of Meiosis ll

• Prophase II: Nuclear envelope disappears, fibers form. 

• Metaphase II: fibers align double chromosomes across the center of the cell (vertical now) 

• Anaphase II: Fibers separate sister chromatids that migrate to opposite sides 

• Telophase II: Nuclear envelope reappears. Each nucleus has single chromosomes. Daughter cells are haploid and genetically different from each other and parent. 

Mitosis vs. Meiosis

Mitosis makes 2 diploid daughter cells that are genetically identical

Meiosis makes 4 haploid daughter cells that are genetically different.

Genetic Diversity in Meiosis: Crossing over

1. Prophase I 

2. Nonsister chromatids of double homologous chromosomes exchange segments 

3. Result: Recombinant Chromatids 

Genetic Diversity in Meiosis: Random Assortment

1. Metaphase I/II 

2. The order of homologous pairs or chromosomes during metaphase can line up differently. 

Genetic Diversity in Meiosis: Fertilization

It's random, so any gamete can contribute to the diploid nature of the offspring. 

Common ancestry can be proven through_______

• shared conserved and fundamental processes, including common features and core metabolic pathways. For example, all organisms use nucleic acids to store and transmit genetic information, and ribosomes to synthesize proteins based on nucleic acid sequences

Pedigree

• visual representation tracing the history of a trait through familial generations, where perpendicular lines represent offspring, circles are females, squares are males, and shaded individuals are affected

  • Autosomal dominant traits: show a pattern of affected offspring with affected parents

  • Autosomal recessive traits: show a pattern of affected offspring with unaffected parents

Rules of Probability

• A OR B: add them / A AND B: multiply them

Hypothesis testing

• used by scientists to reject or fail to reject statistical hypotheses, helping determine whether differences in numerical data are due to the independent variable or to chance

Null hypothesis

• states there is no relationship or no difference between two groups of data in an investigation

Alternative hypothesis

• states observed results are due to a nonrandom cause

Chi square goodness of fit test

• determines whether there is a significant difference between two groups of data, and observed outcomes are compared to expected outcomes

  • This can be used to test whether two traits are linked; if they are linked, there will be a significant relationship between the two traits. To find expected values, you complete a dihybrid cross

  • If the chi square value is less than the critical value, fail to reject the null hypothesis. If it is greater, reject the null hypothesis

Non mendelian genetics

do not follow Mendel’s predicted ratios

Non-medelian genetics: Linked genes

• genes that are adjacent/close to each other on the same chromosome, and are inherited together. So, they are less likely to be separated during crossing over in meiosis. 

Non-medelian genetics: Recombination

• the process where genetic material is exchanged between chromosomes or within regions of the same chromosome, resulting in new combinations of genes

Non-medelian genetics: Map distance

• tells how close together a pair of linked genes is, and is determined by how frequently a pair of genes participates in a single crossover event. Linked genes have a recombination frequency of less than 50%

Non-medelian genetics: Sex-linked genes

• traits determined by genes located on sex chromosomes

  • Since the Y chromosomes carry less genetic information, most sex-linked alleles are carried on the X chromosome. Thus, biological females can be carriers, and males are more likely to have recessive sex-linked allele phenotypes

  • Sex-linked recessive pedigree: pattern of affected offspring with unaffected parents, biological males more likely to be affected than females, and female carriers are half shaded circles

Many traits are the product of ________

multiple genes acting in various combinations, and these traits don’t segregate in Mendelian patterns

Some traits result from non-nuclear inheritance:

• Chloroplasts and mitochondria contain their own non-nuclear genome, and are randomly assorted to gametes and daughter cells during cell division

• Mitochondria are transmitted to the egg and not sperm in animals, and the ovule and not pollen in plants (maternally inherited trait)

• Traits determined by chloroplast and mitochondria DNA don’t follow Mendelian rules 

Phenotypic Plasticity

• the ability of one genotype to produce more than one phenotype. This is because environmental factors affect gene expression. So, phenotypic diversity could be due to environmental factors rather than genetic diversity

Law of Dominance

presence of recessive alleles

Law of Segregation

• The separation of alleles during gamete formation. Each gamete receives only one parental allele, so there’s more varied combinations of alleles when fertilization occurs. 

Law of Independant Assortment

• Genes are sorted into gametes independently (genes are not linked!) Not connected to inheritance of any other gene 

Random Fertilization

• Any unique sperm can join with any unique egg by a female 

Mutated alleles can be _____

inherited.

• Randomly distributed into gametes, can contribute to genetic diversity, but also genetic disorders if variations are negative 

• Nondisjunction is the failure of chromosomes to fully separate (too many or too few chromosomes in sex cells)

Triple X syndrome

• caused by malformation of egg or sperm, resulting in offspring with more than 2 sex chromosomes 

Patterns of Inheritance can ________

be analyzed to determine how chromosomes were inherited (the questions that ask you to determine type of inheritance) 

• Certain genetic disorders can be caused by a single mutated allele that is passed from parent to offspring 

• Parent to offspring inheritance can be analyzed to determine patterns of gene transmission 

• Mutations or malformations in gametes can result in disorders not from parents 

How to determine inheritance pattern:

• Are there unaffected parents with affected offspring? 

  • YES - recessive

    • Can an affected father pass it to his son?

      • YES - Autosomal recessive 

      • NO - X linked recessive

  • NO - dominant 

    • Can an affected father pass it to his son?

      • YES - Autosomal dominant 

      • NO - X linked dominant