BIO 189: Chapter 8- DNA Replication, Binary Fission and Mitosis

What is a gene and what is a genome?

A gene is a segment of DNA with instructions for RNA or protein while a genome is the sum of a organism’s DNA

What are the characteristics of a Prokaryotic genome?

Singular circular chromosome

Located in nucleoid region (central region of cell)

Includes plasmids (smaller DNA circles containing one or few genes)

What are the characteristics of Eukaryotic genome?

Multiple linear chromosomes

Located in the nucleus

Associated with histone “packing proteins”

Label from left to right bottom

Cell, nucleus, chromosomes, gene, protein

What is a karyotype?

Karyon: Kernel/seed/nucleus

Typos: General form

What does the human karyotype contain?

23 pairs of chromosomes (1 set from mom and 1 set from dad)

What are the 22 pairs called?

Autosome chromosomes

What is the 23rd pair and what does it determine?

Sex chromosomes and it determines biological sex

This karyotype represents what?

Typical human karyotype with no chromosomal mutations

Differential gene expression results in different cell types from the?

Same set of instructions

Human DNA is about 99.9% identical to other humans and what else?

99.1% to chimps

90% to mice

85% to zebra fish

50% to bananas

What is cell theory?

All cells come from pre-existing cells

What is cell division?

One “parent” cell duplicates all cellular contents then divides (splits) into two new daughter cells

What is the process of Prokaryotic cell division consist of?

DNA Replication

Chromosome Segregation

Cytokinesis

Binary Fission

What is the process of eukaryotic cell division consist of?

Mitosis which is the cell division in body cells (somatic) in multicellular organisms

What is cell division critical for?

Growth and development

Wound repair

Tissue regeneration

Microbial fission/budding

What is apoptosis?

Programmed cell death, regulated by a class of protein (degrading enzymes called caspases)

What are some reasons for cells to commit suicide?

Development

Injured

Damaged

Infected

What is a somatic cell cycle?

Cell division to cell division

What are the two cell life phases?

Interphase and Mitosis

What is interphase and what does it consist of?

The majority of a cell’s life cycle will be spent here, and it consist of 3 sub phases

What are the 3 sub phases of interphase?

G1: Normal cell function and cell growth

S: DNA replication

G2: Additional growth and preparation for division

What is mitosis and what does it consist of?

The parent cell rapidly divides into two daughter cells and have four stages

What are the four stages of mitosis

Prophase, Metaphase, Anaphase, and Telophase/Cytokinesis

When does DNA replication occur?

Before cell division

What does a parent cell need to do before dividing and where does this occur?

DNA (genome) and in the S phase (synthesis phase)

What do promotor like regions do and what does it produce?

It recruits various enzymes to the origins of replications and splits DNA strand producing a replication fork

What does a DNA polymerase associate with at replication forks?

Two of the original DNA strands

What is semi-conservative replication?

Each parental strand serves as template for new complementary strand

What are the three essential enzymes in DNA replication?

Helicase: Unwinds and Unzips DNA

DNA Polymerase: Building polymers of DNA

Ligase: Tie up or join strands

What occurs during Prokaryotic Binary Fission?

Parent cell contains one chromosome

DNA replicates and attaches to cell membrane

Membrane growth moves DNA molecules apart into new cell walls

Split occurs and two daughter cells are created

What are the mechanisms of prokaryote evolution?

Random DNA mutations may produce new traits

Horizontal gene transfer (genes coming from something else)

What are the three types of horizontal gene transfer?

Transformation (bacterium takes up foreign DNA & adds it to its genome)

Conjugation (donor cell and recipient form a plasmid and make contact through a pilus)

Transduction (DNA is transferred from a virus)

What is Naked DNA and where is it found?

DNA not associated with any histone proteins, found during DNA synthesis and active gene expression

What is chromatin?

DNA wrapped around histone proteins

What is loose configuration?

DNA compacted but allows for easy access to genes if needed

What is common configuration?

When cell is not undergoing cell division

What are chromosomes and where are they found?

Highly condensed (compacted) chromatin, found only during active cell division/mitosis

What are the same pair of chromosomes called?

Homologous chromosomes

During the S phase of the cell cycle, what does the semi conservative DNA replication result in?

Two identical sister chromatids attached by protein centromere

At what point does DNA fully condense during the cell cycle?

Prophase

When does chromosome duplication occur?

Interphase after the S-phase

The dynamic movements of chromosomes and cellular components during mitosis is dependent on what?

Microtubule cytoskeletal elements (Largest cytoskeletal fibers are made from tubulin protein dimers)

What are centrosomes?

Organelle made of two centrioles that makes and organizes microtubules during mitosis

What occurs during G2 Interphase

DNA replication finished

Cellular resources for mitosis are accumulated

Centrosomes duplicate

What occurs during early prophase?

Chromosomes condense and become visible. Spingdle forms as centrosomes move to opposite poles

What occurs during late prophase?

Nuclear envelop breaks up and spindle fibers attach to chromosomes’ sister chromatids

What occurs during metaphase?

Nuclear membrane is disintegrated

Microtubules have attached to sister chromatids

mitotic spindle is formed (cage like)

All 46 chromosomes are lined up at cell midline or metaphase plate

What occurs during Anaphase?

Microtubules begin to pull sister chromatids apart toward opposite poles, cell membrane elongates

What occurs during telophase?

Spindle fiber microtubules begin to disintegrate

two nuclear membranes form

chromosomes decondense into chromatin

What occurs during cytokinesis?

Cytoplasm and organelles are split

In animal cells how does cytokinesis occur?

Contractile ring of proteins makes cleavage furrow

Cells pinch off

In plant cells how does cytokinesis occur?

Cell wall containing vesicles are sent to midline (cell plate) between nuclei

Vesicles fuse and cell wall is established

What are the cell cycle checkpoints?

G2 phase: Is genome damaged? Does the cell have the resources to continue into mitosis?

Mitosis: Were the genomes separated properly?

G1 phase: Is there a signal to divide?

S phase: Is the genome properly replicated?

How can the cell cycle go wrong?

If DNA mutations are not eliminated and accumulate which could cause tumors or cancer

What are benign tumors?

Uncontrolled cell division contained in a tough capsule (size is limited and does not spread)

What is a malignant tumor?

Uncontrolled cell division with no capsule and can enter into circulatory systems and seed in new regions of the body