Biology 32 Unit 1

Chromosome

A length of Dna and associated protein: condensed form of genetic material

Sex chromosomes and Autosomes

Two types of chromosomes are:

Sex chromosome

X or Y chromosome; determines genetic sex

Autosome

Chromosome other than sex chromosome

Chromatin

Non-condensed form of genetic material that predominates for most of the life cycle of the cell. Not get organized into chromosomes

DNA (deoxyribonucleic acid)

A molecule of nucleic acid that governs processes of heredity in the cell of organisms. Where genetic information of a cell is contained

Gene

Governs expression of a trait

Allele

One of the different forms of the same gene

Cell cycle

Life cycle of a cell

Somatic cell

Body cell

46 chromosomes. 22 pairs of autosomes, 1 pair of sex chromosomes

How many chromosomes do human somatic cells have?

Diploid (2n)

Cell with two pairs of homologous chromosomes

Homologous chromosomes

Chromosomes with the same gene sequence

Interphase

Growth stage of cell cycle

G1, S, and G2

Three phases in interphase

G1 Phase

The cells grow quickly during this phase, making many new cell molecules (except DNA).

Protein Synthesis

Organelles are produced

Increase volume of the cytoplasm

S phase

At this phase in the cell cycle, DNA in the chromatin replicates to create an identical copy of DNA.

Cell duplicates its DNA

Sister chromatid

One of two chromosomes that are genetically identical and held together at the centromere

Centromere

The specialized DNA sequence of a chromosome that links a pair of sister chromatids

G2 Phase

This second growth stage lets the cell rebuild its reserves to prepare for division. The cell manufactures proteins and other molecules to make structures required for division of the nucleus and cell.

Organelles are produced

Increase volume of the cytoplasm

Interphase ends when the cell begins the process of nuclear division

Mitosis and cytokinesis

Two main processes in cell division

Mitosis

Division of genetic material and the cell’s nucleus.

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

A separation of the cytoplasm and organelles to form two separate daughter cells

Growth (single cell to trillions), Maintenance (replace warn/dead cells), and Repair (regenerate damaged tissues)

Three functions of mitosis and cytokinesis

1. The chromatin condenses into tightly packed
chromosomes.
2. The nuclear membrane breaks down, releasing the chromosomes into the cytoplasm.
3. The nucleolus disappears.
4. One pair of cylindrical organelles, called centrioles, moves apart to opposite poles of the cell.

What happens during prophase

Centriole

Cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.

1. The spindle fibres guide the
chromosomes to the equator, or
centre line, of the cell.
2. The spindle fibres from opposite poles attach to the centromere of each chromosome.
3. Each pair of sister chromatids is considered to be a single chromosome as long as the chromatids remain joined at the centromere

What happens during metaphase

1. Each centromere splits apart and the sister
chromatids separate from one another.
2. The spindle fibres that link the centromeres to the poles of the cell shorten.
3. As these fibres shorten, sister chromatids are pulled to opposite poles. At the same time, other microtubules in the spindle apparatus lengthen and force the poles of the cell away from one another.
4. At the end of this phase, one complete diploid set of chromosomes has been gathered at each pole of the elongated cell

What happens during anaphase

1. Telophase begins when the chromatids have reached the opposite poles of the cell.
2. The chromatids begin to unwind into the longer and less visible strands of chromatin.
3. The spindle fibres break down.
4. A nuclear membrane forms around each new set of chromosomes, and a nucleolus forms within each new nucleus.

What happens during telophase

Cleavage Furrow

An indentation that appears in a cell’s surface when the cell is preparing to divide. The indentation deepens until the cell is pinched in two.

skin cells, because they are replaced frequently

An example of a cell that divides frequently:

nerve cells

An example of a cell that divides infrequently, or not at all

maintenance period

A rest period during which the cell seems to be resting

no

Do plant cells have centrioles?

A membrane that forms between two daughter nuclei in a plant cell. It extends across the diameter of the vell, and it is then reinforced by cellulose and protein to create a new cell wall.

Cell plate

cancer

uncontrolled cell division

Quality control checkpoints

Points that are built into the cell cycle to ensure that each cell meets a certain standard.

G1/S

Checkpoint near the end of G1 phase, a period of rapid growth and metabolic activity. Checks for DNA damage to ensure that DNA synthesis in S phase is successfull.

They either undergo repair or, if repair isn’t possible, programmed cell death (apoptosis).

What happens to cells with damaged DNA at quality control checkpoints?

Maintains healthy cell reproducyion throughout an organism’s lifetime.

Result of properly working checkpoint system

it produces a malfunctioning protein or no protein at all, and as a result, uncontrolled cell division can occur (development of cancer).

Results of regulatory proteins becoming altered

Cancer surgery, radiation therapy, chemotherapy, targeted therapy, hormone therapy, stem cell transplants

6 examples of cancer therapies

cancer surgery

removes the tumour and nearby tissue during an operation

Location and type of cancer

Type of surgery

Factors to consider for cancer surgery

Pain, fatigue, appetite loss, other organs, swelling, drainage, infection, bruising, numbness, and
bleeding.

Side effects of cancer surgery

Radiation therapy

cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumours

At high doses, radiation therapy kills cancer cells or slows their growth by damaging their DNA. Cancer cells whose DNA is damaged beyond repair stop dividing or die. When the damaged cells die, they are broken down and removed by the body.

How does radiation therapy work?

cancers of the head and neck, breast, cervix, prostate, and eye

Radiation therapy is most commonly used to treat which kinds of cancers?

Fatigue

Hair loss

Nausea and vomiting

Skin changes

Headache

Blurry vision

Swelling (Edema)

Tenderness

Cough

Shortness of breath

Sexual problems (men) Fertility problems (men) Sexual problems (women) Fertility problems (women)

Urinary and bladder changes

Diarrhea

Side effects of radiation therapy

Chemotherapy

A drug treatment that uses powerful chemicals to kill fast-growing cells in your body

Chemotherapy is most often used to treat cancer, since cancer cells grow and multiply much more
quickly than most cells in the body.

Which therapy is most often used to treat cancer, and why?

To Cure cancer (can be used as sole/primary treatment)

After Other Treatments (to kill hidden/ remaining cells)

To Prepare for Other Treatments (to shrink tumour)

To ease signs and symptoms (relieves signs by killing some cells: palliative chemotherapy)

4 situations when chemotherapy is used

Nausea Vomiting Diarrhea Hair loss Loss of appetite
Fatigue Fever Mouth sores Pain Constipation
Easy bruising Bleeding

Side effects of chemo therapy

Targeted Therapy

a cancer treatment that uses drugs to target specific genes and proteins that are involved in the growth and survival of cancer cells.

Breast Cancer, Leukemia, Colorectal Cancer,
Lung Cancer, Lymphoma, Melanoma

Common cancers treated with targeted therapy

* Block or turn off signals that tell cancer cells to grow and divide
* Prevent the cells from living longer than normal
* Destroy cancer cells

What can targeted therapy do?

Diarrhea Liver problems Blood clotting Slow wound healing
High blood pressure Fatigue Mouth sores Nail changes Loss of hair color
rash and dry skin

Side effects of targeted therapy

Hormone therapy

A cancer treatment that slows or stops the growth of cancer that uses hormones to grow. Also called hormonal therapy, hormone treatment, or endocrine therapy.

Treat cancer (lessen chance of recurrence, stops/slows its growth)

Ease cancer symptoms (reduce/prevent symptoms when surgery/radiation is unavailable)

What is is hormone therapy used to?

* Hormone therapy is used to treat prostate and breast cancers that use hormones to grow.
* Hormone therapy is most often used along with other cancer treatments.

When is hormone therapy used?

hot flashes loss of interest in or ability to have sex weakened bones
diarrhea Nausea enlarged and tender breasts fatigue

Side effects of hormone therapy (prostate cancer)

hot flashes, vaginal dryness ,changes in your periods if you have not yet reached menopause, loss of interest in sex, nausea, mood changes, fatigue

Side effects of hormone therapy (breast cancer)

Stem cell transplant

healthy stem cells are placed in your body to help your bone marrow start to work properly. The new stem cells make healthy blood cells.

* It is used when stem cells or bone marrow have been damaged or destroyed by cancer or
disease.
* Used to treat some cancers such as leukemia, lymphoma, multiple myeloma and
neuroblastoma.
* It may also be used after high-dose radiation and chemotherapy to treat the cancer.

When are stem cell transplants used?

The stem cells in the bone marrow turn into red blood cells, white blood cells and platelets. When these cells mature they move into the peripheral blood. If the bone marrow is damaged or destroyed, it can’t make normal blood cells. In a stem cell transplant, healthy stem cells are placed in your body to help your bone marrow start to work properly. The new stem cells make healthy blood cells.

How do stem cell transplants work?

A stem cell transplant is very complex.
It can take 6 to 12 months or longer for your blood counts to be back to normal and your immune
system to work well.

How long for a stem cell transplant to make blood count back to normal?

All of the side effects associated with chemotherapy and radiation they are common as well as: Low blood cell counts, Infection, Bleeding, Anemia, Veno-occlusive disease, Digestive system problems - sore mouth and throat, nausea and vomiting, loss of appetite, weight loss, Diarrhea

Side effects of stem cell transplant

Haploid

A cell with half the number of chromosomes. Contains unpaired chromosomes

Meiosis

Cell division that produced haploid gametes from a germ cell

Germ cell

gamete producing cell

Gametes

an organism’s reproductive cells. also referred to as sex cells

Ova or egg cells

female gametes

sperm

male gametes

The gametes of an organism must contain half the number of chromosomes as the somatic cells of the organism

What must be possible for a diploid zygote to have genetic information from both parents and the same number of chromosomes as its parents?

Reduction division

Also referred to as meiosis, because it is a form of cell division that produces cells with fewer chromosomes than the parent cells

Recombination

The products of meiosis have different combinatinos of genes. Genetic recombination gives rise to offspring that are genetically distinct from one another and their parents

Meiosis 1 and meiosis 2

Two complete rounds of prophase in meiosis

Germ cells proceed through interphase before
dividing.
Chromosomes are replicated during the S
phase of interphase.
This also occurs before a germ cell begins
meiosis. At the start of meiosis, therefore,
a germ cell contains duplicated
chromosomes.
Each chromosome is made up of a pair of
identical sister chromatids held together
at the centromere.

What happens in Interphase (meiosis)

Synapsis

aligning of homologous chromosomes in prophase 1

Tetrad

A pair of homologous chromosomes that is made of up of four chromatids

non-sister chromatids

chromatids that do not belong to the same chromosome

he chromosomes, however, do not line up in single file as they do in mitosis. Instead, they line up as homologous pairs. In each pair, one homologous chromosome is positioned on one side of the cell’s equator, and the other homologous chromosome is positioned on the other side of the cell’s equator.

What happens in Metaphase 1 (meiosis 1)

the spindle fibres shorten. This causes the homologous chromosomes to separate from one another. The homologues move to opposite poles of the cell. Because the sister chromatids are still held together, the centromeres do not split as they do in mitosis. The result is that a single chromosome (made up of two sister chromatids) from each homologous pair moves to each pole of the cell.

What happens in anaphase 1 (meiosis)

Other cells go through telophase I following anaphase I. In telophase I, the homologous chromosomes begin to uncoil and the spindle fibres disappear. The cytoplasm is divided, the nuclear membrane forms around each group of homologous chromosomes, and two cells are formed. Each of these new cells contains one set of sister chromatids and is now haploid.

What happens in telophase 1 (meiosis)?

At the end of cytokinesis I, two different daughter cells are formed, each with half the number of chromosomes as the parent cell (having 23 chromosomes having 23 pairs of chromatids).

What happens at the end of cytokenesis 1? (meiosis)

The nuclear membrane initiates to break down, and the spindle fibers appear again. Each centriole divides, forming two pairs of centrioles. Chromosomes do not replicate any further in this phase of meiosis and begin migration towards the center of the cell.

What happens in prophase 2?

Chromosomes arrange on the equator of the cell with the help of the spindle fibers. The centrioles are now at opposite poles in each of the daughter cells. Centromere divides, producing two sister chromatids, now known as daughter chromosomes, with the spindle fibers attached to each chromosome.

What happens in metaphase 2? (meiosis)

The daughter chromosomes are pulled towards the opposite poles of the cells
with the help of the spindle fibers.
At the end of anaphase II, each end of the cell contains a complete set of
chromosomes.

What happens during anaphse 2? meiosis

The nuclear membrane forms around each chromosome with the disappearance of
the spindle fibers.
Nucleolus reappears as the cell prepares for the second round of cytoplasmic
division.

What happens during telophase 2? (meiosis)

Identical to cytokenesis 1. Resulting in four non-identical, haploid daughter cells, each having half chromosome number of the original parent cell.

What happens at the end of cytokenesis 2?

Independant Assortment (creating different gametes that carry different combinations of pat/maternal chromosomes)

Crossing Over (exchange of genetic material between maternal/paternal chromosomes)

Two ways genetic variation is ensured:

Independant assortment

The______ of homologous chromosomes during metaphase I results in gametes that have different combinations of parental chromosomes.

Crossing over

Exchange of genetic material between non-sister chromatids

While they are lined up side by side in prophase I, non-sister chromatids may exchange pieces of chromosome

Spermatogenesis

Process of male gamete production

spermatogonium

Diploid germ cell from which sperm are produced.

Beginning at puberty, spermatogonia are stimulated to divide by mitosis to form two daughter cells. One of these cells replenishes the spermatogonia cell population, and the other develops into a primary spermatocyte.

How are spermatogonia stimulated?

Following meiosis II, the spermatids go through a final set of developmental stages in order to develop into mature sperm cell.

How do spermatids develop into mature sperm cells?

The primary spermatocyte undergoes meiosis I to form two secondary spermatocytes. The secondary spermatocytes then undergo meiosis II to form four spermatids.

How do spermatocytes develop into spermatids?

sperm cell

male gamete

A mature sperm is a tadpole-shaped structure, about 0.05 mm long.

How long is a sperm cell?