BIO Ch. 10

Genome

All of the cells DNA

Circular shape

Genome in prokaryotes

Linear double-stranded shape

Genome in eukaryotes

3 billion pairs

How many PAIRS of nitrogenous bases make up one complete copy of the human genome?

Chromosomes

23 discrete pieces of genome put into strands of DNA

Ploidy

Refers to how many complete sets (copies) of the genome an organism carriers in its cells

Haploid

Diploid

Triploid

1 copy

2 copies

3 copies

Somatic

Body Cells

2 pairs

23

Number of chromosomes in the human genome

Gametes

Sex Cells

Males - Sperm

Females - Eggs

1 pair

Haploid

What type of ploidy (copies) is in human gametes?

Diploids

Most eukaryotic cells are _______

Homologous Pairs

Matched pairs of chromosomes in a diploid organism

Homologues

Same/Similar genes in exactly the same location

The X and Y Chromosomes

What pair of homologues go together but are not the same?

Tightly Packed

DNA must be _____ _____ to fit into a cell’s nucleus

Histones

Proteins that help to compact the DNA by wrapping the DNA around itself

Nucleosomes

Beads on a string

Short Stretches of DNA double helix wrap around a core of eight histones proteins at regular intervals along the entire length of the chromosomes

Chromatin

Name for multiple nucleosomes in a strand

Loosely constructed Chomosomes

30nm chromatin fiber

Multiple Chromatin are linked by linking DNA into what?

Loops are formed and further compressed

What happens after chromatin fibers are formed?

Chromosomes

Multiple compressed chromatin loops form what?

Cell Cycle

Order of events when a cell goes through the process of growing and eventually going from 1 parent cell to 2 daughter cells

Regulation

What is key in the success of the cell cycle?

Interphase

The cell grows and replicates DNA in this process (G₁, S, G₂)

G₁ Phase

First Growth

Preparing to make more DNA

Needs tremendous amount of Energy

Can be limited by lack of Nutrients or Irregular Temps

Quiescence (inactivity)

Instead of cells splitting some will leave and carry out different functions but won’t be doing carrying out the cell cycle

1/3

Human somatic cells spend about ____ of the cell cycle in the G₁ phase

S Phase (Synthesis)

Process of DNA replication which results in identical copies of each of the 46 strands of DNA in the cell

Centromere (Pairs are called Sister Chromatids)

S Phase: Place where strands of newly synthesized DNA remain firmly connected to each other

Centrosome

S Phase: Organelle that consists of two centrioles stacked on each other and pull the sister chromatids apart

Centrioles

S Phase: Makes up the centrosome and is composed of microtubule fibers arranged in a cylinder

In the centrosome

Where are microtubules made?

G₂ Phase (Second Growth)

The stage where the cell is replenishing its energy stores and also dismantling its cytoskeleton in order to make final preparation before splitting

Mitotic Phase

Multistep process where newly synthesized DNA strands further condense, are aligned, separated, and move into two separate and identical daughter cells

Karyokinesis (splitting of the nucleus)

First step of Nuclear Division

Cytokinesis

Separation of the cytoplasmic contents and cytoplasm

Prophase

Chromatin condenses down and sister chromatids become visible

Nuclear Envelope breaks down

Microtubules called spindle fibers, extend from the two centrosomes and as the fibers lengthen, they begin to move the centrosomes to opposite poles

Prometaphase

DNA of sister chromatids continue to condense

Kinetochores (protein structure) appear at the centromeres of each sister chromatid

Mitotic spindle fibers from the centrosomes bind with the kinetochores

Spindle fibers continue to form and elongate across the span of the cell

Kinetochores

Proteins that connect to the centromeric region

Mitotic spindle microtubules connect to this to bring the sister chromatids to opposite sides of the cells

Metaphase

When chromosomes are lined up

All the sister chromatids are lined up in a plane called the metaphase plate

DNA sister chromatids is maximally condensed

Centrosomes reach the poles of the cell

Microtubule spindle fibers are fully formed and create mitotic spindles

Metaphase plate

When all the sister chromatids are lined up in a plane

Anaphase

Where the pulling happens

The connection between the sister chromatids at the centromere breaks down and the sister chromatids separate

Movement of the microtubules causes the cell to elongate

Telophase

Chromosomes reach opposite poles and begin to de-condense back into chromatin

Mitotic spindles are broken down into monomers that will be used to reassemble the cytoskeleton

Nuclear Envelopes reform around each set of chromosomes (forming new nucleus)

Cytokinesis

Begins in the onset of anaphase and takes place throughout telephase

Contractile ring squeezes the cell to prepare it for separation

Cleavage Furrow splits the membrane and pulls the equator inward, pinching the membrane into two

Contractile Ring

Squeezes the cell during cytokinesis to prepare for it to split

Cleavage Furrow

Actin Filaments that pull the equator inward that pinches the membrane and splits it into two

Cell Plate

Cytokinesis in plants where the Golgi vesicles bring glucose to the middle of the splitting cell and create a cell plate that will turn into the cell wall

Takes place during telophase

Binary Fission

Prokaryotes reproduce by this process

Single, Circular Molecule of Double-Stranded DNA

The genome in prokaryotes is found as a ______ ______ ______ found in the nucleoid region

Steps of Prokaryotic Cell Division

Loops of DNA move to opposite ends of the cell

A new membrane and cell wall are made between the two loops called the septum

When new walls are in place the daughter cells separate

Mutations

a small percentage of DNA replications errors result each completed cell cycle, even when regulatory mechanisms function correctly

passed to each successive pair of daughter cells and accumulate

occur in coding regions and are not corrected

Cancer

result of gene mutations that give rise to faulty proteins that play a key role in the cell cycle

Proto-oncogenes

normal genes that code for positive cell cycle regulators

Oncogenes

if mutated, these normal genes can become ____ or genes that lead to an unnatural increase in the rate of cell cycle progression

Tumor Suppressor Genes

Genes that code for negative cell cycle regulators

If mutated, these normal genes might not be able to halt the cell cycle if there is a problem