Bio Unit 6

Chromatin

Loosely packed DNA found in non-dividing cells

Chromosome

Tightly wound DNA found in ACTIVELY dividing cells

Linker DNA

Stretch of DNA not wrapped around histones that connect nucleosomes

Sister Chromatids

Chromatids connected at the centrosome

Explain how DNA packaging relates to gene expression

Chromosomes make genes inaccessible

Gap 1 (Part of cell cycle - interphase)

GROWTH. The cell doubles in size, metabolic processes like protein synthesis occur, mitochondria divide using binary fission.

Synthesis (Part of cell cycle - interphase)

DNA is replicated within the nucleus

Gap 2 (Part of cell cycle - interphase)

Continued growth, synthesizing microtubules and other proteins necessary for cell division

Mitosis

The division of the nucleus. Splits into 2 IDENTICAL daughter cell

Cytokinesis (part of MITOSIS)

Division of the cytoplasm

Prophase (part of MITOSIS)

PREPARE. Chromatin condenses into chromosomes so DNA doesn’t get lost. Nuclear membrane breaks down and spindle forms

Metaphase (part of MITOSIS)

MIDDLE. Duplicated chromosomes line up along the metaphase plate at the equator of the cell. Spindle fibers attach to the chromosomes at the kinetochore - motor proteins that are located in the centromere region

Anaphase (part of MITOSIS)

APART. Centromere splits and sister chromatids separate and move away from each other towards the plots of the cell. Spindle fibers are responsible for chromosome movement

Telophase (part of MITOSIS)

TWO. Chromosomes condense into chromatin, nuclear membrane reforms around the two new nuclei. Spindle fibers disassemble

Apoptosis

Programmed cell death

Why is it important for cell cycle to be tightly regulated

To maintain healthy tissues

Asexual reproduction

New cells are genetically identical to the original cell

Pros of asexual reproduction

Large number of offspring in a short amount of time, less energy, less complex

Cons of asexual reproduction

Doesn’t increase genetic diversity, harmful mutation

Pros of sexualreproduction

Increases genetic info, advantageous in changing environments

Cons of sexualreproduction

Fewer organisms in more time, more complex

Type of sister chromatids that cross over are..

bivalent/tetrad

Recombinant chromatid

The chromosome that changed from crossing over

Non-recombinant chromatid

Chromosomes that didn’t change during crossing over

Zygote

Fertilized egg cell

Meiosis

Division of the nucleus. Splits into 4 unique daughter cells

Alleles

Different versions of the same genes

How are alleles created?

Mutations to a gene sequence, many are due to SNPS

True breeding

Line of plants that self pollinate - so they’re identical

Mendel’s experiment - P generation

2 true breeding plants of opposite traits: True breeding white flower and true breeding purple flower and created both purple and white flowers

Mendel’s experiment - F1 Generation

Cross pollinated the 1st generation with the true-breeding plants: 100% turned purple and made hybrids

Mendel’s experiment - F2 Generation

Allowed the hybrids to self-pollinate: Offspring exhibited both versions of the traits, ¾ purple flowers and ¼ white flowers

2 Alleles - concept of Mendelian genetics

There are 2 copies of each gene, one on each chromosome in a homologous pair (at the same loci) could be the same allele or different alleles

Biparental Inheritance

For each trait, an organism inherits 2 alleles, 1 from each parent/gamete. Could be the same or different

Autosomal traits

Traits that exhibit Mendelian genetics have genes that are found on the autosomes

Dominance vs. Recesiveness

When an organism has 2 different alleles, the dominant allele will be the one that’s expressed.

Law of Segregation

In the parent, the alleles of each trait segregate into each gamete so each gamete on receives one copy of each gene

What violates the law of segregation?

Non-disjunction

Genotype

Combination of alleles in an individual

Phenotype

Genotype determines ________. Eye color, blood type, height, etc.

Gamete

Sperm or egg

Homozygous Dominant

2 copies of the same dominant allele - FF

Homozygous Recessive

2 copies of the same recessive alleles - ff

Heterozygous

1 copy of each allele - Ff

Non-disjunction

the failure of homologous chromosomes or sister chromatids to separate properly during cell division

Law of independent assortment

Each pair of alleles segregates independently of all other pairs of alleles during gamete formation

Autosomal Dominant Inheritance

Filled in shapes are either AA or Aa.

If both parents have the trait, and at least one of their children doesn’t have the trait, it must be

Autosomal Dominant

Autosomal Recessive Inheritance

Filled in shapes are aa.

Sexlinked Recessive Inheritance

Means filled in shapes are X^aX^a (female) and X^aY (male)