AP Biology Unit 5 (Meiosis, Sexual Reproduction, Hereditary)

Assignment. Day 1: Sexual Reproduction + Meiosis Assignment. Day 2: Chromosomes and Genetic Recombination Assignment. Day 3: Sex Cell Creation, Fertilization, and Basic Genetics Assignment. Day 4: Drosophila and Non-Mendelian Inheritance Assignment. Day 5: Pedigrees

Meiosis

cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell.

important for sexual reproduction

Stages of Meiosis

1. Prophase 1 (2 Chromosomes stick together forming a → Tetrad → Crossing Over occurs and pieces of homologs switch positions)

2. Metaphase 1 (independent assortment - each tetrad could align one way or the opposite, leading to the distribution of genes and traits to be irregular)

3. Anaphase 1

4. Telophase/Cytokinesis 1 (the seperation is important becuse it provides the means for cell division and the formation of idependent cells)

5. Prophase 2

6. Metaphase 2

7. Anaphase 2

8. Telophase/Cytokinesis 2 (the seperation is important becuse it provides the means for cell division and the formation of idependent cells)

Crossing Over

2 Chromosomes stick together forming a → Tetrad → Crossing Over occurs and pieces of homologs switch positions

happens in chiasmata

chiasmata

x shaped regions where crossing over happens

Independent Assortment

each tetrad could align one way or the opposite, leading to the distribution of genes and traits to be irregular

Chromosome

DNA Molecule

Made of two identical DNA Molecules (sister chromatids)

Chromosomes

Person has 46

23 from Mom + 23 from Dad

Gene Locus

1p1.11

Chromosome 1

p arm

location

heredity

transmission / sharing of traits generation → generation

variation

no identicality (inherited variation)

crossing over and independent assortment

genetics

study of heredity and inherited variation

genes

hereditary units (code) “program trains”

gametes

reproductive cells (sperm + egg)

somatic cells

allcells of the body

sexual reproduction

parent + parent = offspring (vary genetically)

asexual reproduction

single individual : passes copies of genes w/o gametes (exact copies) ((clones))

life cycle

generation → generation sequence of stages in reproductive history of an organism, from conception to its own reproduction

karyotype

displayed image of chromosome variants

homologous chromosomes (homologs)

= length = pattern = centromere position

sex chromosomes

x and y (maternal & paternal)

• sets of 23

autosomes

all other chromosomes

diploid cell

cell has two chromosome sets (2n = 46 X)

haploid cell

cell has a single set of chromosomes n = 23 |

fertaalization

haploid sperm + haploid egg = zygote

zygote

fertilized egg

DNA can be seen in

• chromatin

• chromatid

• chromosome

synapsis

DNA breaks are closed up to be ready for a non sister chromatid

synaptonemal complex

zipper structure that holds homologs together

sister chromatid cohesion

sister chromatids are 2 copies of one chromosome