MAR 106 Exam 3

Imported from Quizlet - @Captain_Corgi

What are the three stages of Interphase?

G1, S, G2

How would you describe the life cycle of a prokaryotic cell?

Short/fast

How do prokaryotic cells reproduce?

Binary fission; simple splitting

How would you describe prokaryotes?

Unicellular, whole organism reproduction

How would you describe binary fission?

Cell enlarges, DNA/RNA replication occurs, each copy moves away from each other as cell elongates, plasma membrane grows inward and septum forms, cell divides

What are the two stages of the mitotic phase?

Mitosis, Cytokinesis

Where is the genetic material stored in a Eukaryotic cell?

Nucleus

How are chromosomes formed?

Chromatin is wound around histone proteins

What are histone proteins?

Proteins in which DNA wraps its self around

What are Nucleosomes?

DNA and histone molecules which together form a bead-like structure.

What is chromatin?

uncoiled DNA

What are the steps of chromosome formation?

DNA and histone proteins bind together to form nucleosomes, which forms chromatin

What are kinetochores?

protein complexes associated with centromeres

What are homologous chromosomes?

paired chromosomes with genes for the same traits arranged in the same order

What are sister chromatids?

2 identical copies of DNA held together by a centromere (bottom of chromosome)

How would you describe chromosome replication?

1 Chromatid forms 2 chromatids after mitosis (lines to X)

What information is processed at the G1 checkpoint?

Integrity of DNA, cyclin concentration

What information is processed at the G2 checkpoint?

Integrity of DNA, amount of DNA, cyclin concentration

What information is processed at the M checkpoint?

Alignment of chromosomes

What happens when a cell does not get the "go ahead" at the G1 or G2 checkpoints?

It goes to G0, which is a stalled stage and repairs DNA, or Apoptosis (cell death)

What occurs during apoptosis?

Cell rounds, nucleus collapses, chromatin condenses, nucleus fragments, plasma membrane blisters and blebs form

When is it good for a cell to undergo apoptosis?

• Damaged/Not Efficient

• Infected with Virus

• Organism is metamorphizing or automatizing (shedding)

When is it a good thing for a cell to proceed through mitosis/cell reproduction

• Young organism growing & developing

• Immune system needs backup

• Tissue is damaged & needs replacing

• Stem cells

What are stem cells?

Cells that have the capacity to reproduce indefinitely

pluripotent

Not differentiated stem cells that can serve a variety of purposes

What happens when cells do not heed checkpoints?

Cancer develops

Why does cancer develop?

Accumulation of mutations cause a loss of control of the cells cycle

What are some characteristics of cancer cells?

D - Not differentiated

N - Abnormal Nuclei

T - Tumors, no density-dependent inhibition
A - No apoptosis

What happens if a cancer cell is malignant?

It undergoes metastasis (spreads through the body) and angiogenesis (recruitment of blood vessels)

What is cancer the result of?

Mutations in cell-cycle regulator genes

proto-oncogenes

stimulatory pathway; encode for proteins that stimulate normal cell growth & division

tumor supressor genes

inhibitory pathway; normally inhibit cell division

What are some other mutations that make cancer development likely?

Mutations in genes that code for DNA repair enzymes, mutations that code for telomerase

What is telomerase?

An enzyme that lengthens telomeres

What are telomeres?

Non-gene-encoding nucleotide bases at the end of chromosomes, they shorten with each replication

What are the most common/well studied cancer genes?

p53 (a tumor suppressor gene, turns on other genes that inhibit cell cycle/facilitate apoptosis) BRCA1, BRCA2

How many copies of genetic material do somatic animal cells have?

Two (all genes occur in pairs)

How many pairs of autosomal chromosomes do humans have?

22

How many pairs of sex chromosomes do humans have?

1

What is a karyotype?

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

What is meiosis?

Two nuclear divisions that produce new cells with 1/2 of the original genetic material

Where does meiosis occur within the body?

Spermatogenesis/Oogenesis

What happens to a cell in meiosis?

Diploid (2N) to Haploid (1N)

What does diploid mean?

2 sets of chromosomes

What does haploid mean?

one set of chromosomes

What is spermatogenesis?

Production of sperm via meiosis (spermatocyte splits into 2 secondary spermatocytes, those split into four spermatids, they undergo metamorphosis and turn into sperm)

What are spermatogonia?

Stem cells in the testes that continually produce sperm through the two stages of meiosis

What is oogenesis?

Process by which ova are produced by the female.

Where does oogenesis occur?

Ovaries

What are oogonia?

Stem cells in the ovaries that product primary oocytes only during fetal development

What happens to 1 0Oocytes during meiosis I?

They produce a secondary oocyte

What happens if a sperm is present?

2 Oocyte undergo meiosis II to complete the process of egg formation

What happens in Prophase 1?

Homologous chromosomes pair during synapses (DNA replication)

What happens during Metaphase I?

Homologous chromosome pairs align at the metaphase plate

What happens during Anaphase I?

Homologous chromosomes separate, pulled to opposite poles by centromeric spindle fibers

What happens during Telophase I?

Daughter cells have one chromosome each from homologous pair

What happens during Interkinesis?

Chromosomes still consist of two chromatids

What happens during Prophase II?

Cells from meiosis I have one chromosome from each homologous pair

What happens during Metaphase II?

Chromosomes align at metaphase plate

What happens at Anaphase II?

Daughter chromosomes move toward poles

What happens during Telophase II?

Spindle disappears, nuclei form, cytokinesis takes place

What is the result of Meiosis I and II?

Four haploid daughter cells

What is chromosome nondisjunction?

When chromosomes don't split correctly

What are some examples of chromosome nondisjunction?

Trisomy 21 (Down syndrome), Klinefelter and Turner syndromes

What is a benefit of meiosis/sexual reproduction?

Genetic variation

What is independent assortment?

genes for different traits can segregate independently during the formation of gametes

What is genetic recombination?

Crossing over, when chromatids begin to pair up early in Meiosis I, genetic material is exchanged between non-sister chromatids

What is random fertilization?

Sperm cell chromosomes combine with egg cell chromosomes which means even more possible diploid combos

What are the theories on patterns of inheritance?

Blending theory of inheritance and particulate theory of inheritance

What did Gregor Mendel do?

Breed different variations of garden pea plants in the 1800s

How did Gregor Mendel breed variations of pea plants?

Removed stamens from purple flower, transferred pollen from stamens of white flower to carpel of purple flower, allowed pollinated carpel to mature into a pod, planted seeds

What is an allele?

Alternate forms of a gene that code for one characteristic

What is a dominant allele?

If present, will mask the expression of other alleles

What is a recessive allele?

Will only be expressed if dominant allele is not present

What is a genotype?

Genetic information

What is a phenotype?

Expression of genetic information

While most cells are diploid, what can their genotypes be?

Heterozygous or homozygous

What does heterozygous mean?

One dominant allele, one recessive

What does homozygous mean?

Both alleles are either dominant or recessive

What is a gene locus?

Place on the chromosome where alleles are located

What is a monohybrid cross?

A cross between individuals heterozygous for a single character

What is incomplete dominance/codominance?

A blending of traits (EX: Red + white = Pink)

What are multiple allelic traits?

One gene, more than two possible alleles (EX: Blood type A, B, O)

What is polygenic inheritance?

inheritance pattern of a trait that is controlled by 2 or more genes

What is pleiotropy?

The ability of a single gene to have multiple effects.

What is epistasis/epistatic interaction?

When one gene overrides another

What is chromosome linked inheritance?

Where a gene is located can affect inheritance pattern

What are human x-linked disorders?

Color blindness, muscular dystrophy, hemophilia