Cell Division and Genetics Review

The cell cycle can be divided into two parts: 1) Interphase  the period between cell divisions a) interphase has three parts: 1) G1 – cell growth – cell increase in size and makes new proteins and organelles. 2) S – Chromosomes are replicated. 3) G2 – Preparation for mitosis 2) Cell division – the cell divides into two identical daughter cells a) has two parts 1) mitosis – division of the nucleus 2) cytokinesis – division of the cytoplasm

ProphaseMetaphase Anaphase Telophase Prophase Metaphase

Prophase a) The chromatin condenses to form chromosomes (DNA is visible) b) Centrioles separate and the spindle fiber forms 1) spindle fiber help to separate chromosomes c) The nuclear envelope breaks down

Metaphase a) Chromosomes line up across the center of the cell. b) Each chromosome is connected to a spindle fiber at it’s centromere Anaphase a) Centromeres that join sister chromatids move apart causing the sister chromosomes to separate and become individual chromosomes. b) The chromosomes are located at opposite ends of the cell.

Telophase a) Chromosomes are at opposite ends of the cell. b) Chromosomes lose their shape c) Two new nuclear membranes form.

MitosisMeiosis Purpose of This Type of Cell DivisionGrowth, tissue repair, asexual reproduction Production of _________ for sexual reproduction Parent Cell Chromosome NumberDiploid Daughter Cell Chromosome NumberDiploid Number of Daughter Cells Produced2 4: 4 sperm/mother cell in males but only one egg + three polar bodies/mother cell in females Number of Times DNA is Copied11 Number of Cell Division__1__________2____ Comparison of Mother Cell and Daughter CellsGenetically _same____________Genetically __differenct___________ Shuffling of DNA?_____no_______yes_____ Crossing-over happens?___no_____yes____–during Prophase 1

Vocabulary terms to know: HEREDITY is the passing on of traits from parents to offspring. GENETICS is the branch of biology that studies heredity. CODON is a piece of DNA that codes for the production of a polypeptide chain. TRAIT is a characteristic that is inherited, like eye color or skin color. ALLELES are alternative forms of a gene that produce different choices for a trait, such as brown eyes or blue eyes. DOMINATE traits are expressed if only one allele is present and can mask the presence of recessive alleles. RECESSIVE traits are masked by the presence of a dominant allele, so are only expressed when homozygous. GENOTYPE is the combination of alleles present in an organism.

PEHNOTYPE is outward appearance of an organism: the allele that is expressed. HOMOZYGOUS means that both alleles for a trait are the same—either both dominant or both recessive HETEROZYGOUS means that the two alleles for a trait are different CO-DOMINANCE is an inheritance pattern where the phenotype of a heterozygous organism is an intermediate between the dominant and the recessive traits—neither allele is dominant and capable of masking the presence of the other. SEX LINKED traits are controlled by genes located on the X chromosome. They are passed from mother to son. Hemophilia and red-green colorblindness are examples in humans. MULTIPLE ALLELES refer to traits that have more than one possible allele. In humans, blood type is such a trait: A, B, and O alleles can combine to produce four possible phenotypes: Type A, type B, Type O and Type AB.

Mendel described three laws of inheritance: Law of DOMINANCE – The presence of a DOMINATE allele can mask the presence of a RECESSIVE allele. Law of SEGREGATION –Because each diploid organism has 2 alleles for each trait, it can produce two types of gametes, one with each allele. Law of INDEPENDENT Assortment—genes for different traits are inherited SEPERATELY of each other.

Use a Punnett Square to predict the offspring of a heterozygous tall pea plant with a homozygous short plant. Tall is dominant over short plants.

Patterns of inheritance 1. Vocabulary Terms: a. mutation – a change in the DNA of an organism that can be passed on to offspring b. Non-disjunction – when chromosomes don’t separate from each other correctly c. monosomy– in diploid organisms, when one chromosome of a pair is missing d. trisomy – in diploid organisms, when there is an extra chromosome of any of the pairs e. autosomal – any chromosome that is not a sex chromosome

Tell how each of the following conditions is inherited. hemophilia – sex-linked recessive trait passed from a mother who is a carrier to sons because allele is on the X-chromosome Huntington’s disease – an autosomal dominant gene Down Syndrome – Trisomy 21 in humans causes Down Syndrome Duchenne muscular dystrophy – sex-linked recessive gene colorblindness –Sex-linked recessive trait *** All sex-linked recessive traits are passed from a mother who is a carrier to her son because the defective allele is on the X-chromosome and sons get their only X chromosome from their mother.

Genetic Engineering 1. Genetic engineering is a new field of biology in which genes can be altered from one organism to another. 2. This field has led to the development of oil spill eating bacteria, bacteria that make human insulin for diabetics, and many disease- resistant crops.