Unit 1 - Cell and Cell Division

What three structures are not considered organelles? (hint: they all start with C)

cytoplasm, cytoskeleton, and cell wall

What development enabled scientists to study the function of individual cell organelles?

Ultracentrifugation

Describe ultracentrifugation.

uses a fast centrifuge to separate organelles based on density

What is an advantage of the nucleus and cytoplasm being separated into compartments?

Separates gene transcription (in nucleus) and translation (in the cytoplasm)

also protects DNA in the nucleus (using double membrane) from harmful reactions in the cytoplasm

Advantage of compartmentalization in cytoplasm of cells?

Organelles can store and use concentrations of METABOLITES & ENZYMES which are incompatible with metabolism occuring in cytoplasm of cell

Two examples of organelles where compartmentalization is very useful (think ones that could be harmful to others)

Lysosomes & Phagocytic Vacuole

The structural features viruses share with other organisms could be regarded as...?

Convergent Evolution

What is shared between viruses and living organisms?

Genetic Code

Name two reasons viruses have very rapid rates of evolution.

High replication rate & immune system selects for mutated viruses

Name two examples of rapid evolution.

HIV and Flu

What are the 5 adaptations of the mitochondria - and then explain them!

Outer membrane - channels for pyruvate

Inner membrane - contains proteins of ETC & ATP synthase

Intermembrane space - small space enables quick accumulation of protons

Crystae - more folds which increase SA

Matrix - contains DNA, ribosomes, and all enzymes involved in link reaction & Krebs Cycle

What are the functional benefits of pores & double membrane in the nucleus?

Pores - help mRNA enter cytoplasm when too large for nuclear membrane

Double membrane - allows nucleus to break down into many small vesicles

What protein are vesicles made of?

Clathrin

What is the name of the gene-regulating chemical that causes embryonic stem cells to differentiate into specialized ones?

morphogens

What is a stem cell niche?

A microenvironment that can maintain the cells or promote their proliferation and differentiation

Two examples of stem cell niches...

Bone Marrow & Hair Follicles

Define Totipotent (totally everything)

can differentiate into all types of cells or develop into an embryo

Define Pluripotent (plentiful)

can differentiate into all types of cells BUT embryos

Define Multipotent (multiple)

can differentiate in a limited range of cells

stem cells in adult tissues such as bone marrow are multipotent

Name three adaptations to increase the SA-Volume ratio in cells. Also name two examples!

1. flattening of cells

2. microvilli

2. invagination

erythrocytes (RBCs) & proximal convoluted tubules

Explain cytokinesis in animal cells

A contractile ring of actin and myosin filaments pinches the cell membrane together to split the cytoplasm

Explain cytokinesis in plant cells

Vesicles line up at the equator and will fuse to form a cell plate to achieve splitting

What MUST each daughter cell receive during cytokinesis?

one mitochondrion & other organelles that can only be made by dividing a pre-existing structure

Two examples of uneven division

budding & oogenesis

What does DNA replication produce?

produces a chromosome with two elongated DNA molecules (sister chromatids) held together until anaphase

What is it called when DNA coils around histone proteins?

nucleosomes

What helps move chromosomes during anaphase?

microtubules and microtubule motors

Meiosis I produces what?

2 haploid cells

Meiosis II produces what?

4 haploid cells

What is it called when homologous chromosomes or sister chromatids fail to separate fully during anaphase? Also, give an example.

Non-disjunction; Trisomy 21 (Down Syndrome)

Meiosis is a source of variation through which 3 things?

1. Crossing over

2. Independent assortment

3. Random fertilization

Give 3 examples of cell proliferation

1. Embryonic Development

2. Plant Meristems

3. Tissue Replacement/Healing

What is the purpose of cyclins?

Concentration of cyclins increase and decrease during cell cycle and threshold level of a specific cyclin is required to pass each checkpoint in the cycle.

Mutations in proto-oncogenes and/or tumor suppressor genes (which regulate normal cell growth) cause…

uncontrolled cell division —> which can lead to cancer