BIO 1000 - exam #3 - Matthew Kearley

how many chromosomes are in the human body?

46 chromosomes; 23 pairs

When cells divide what do they produce?

Daughter cells

How do cells come from other cells?

cell division

In humans, somatic cells undergo cell division to produce what?

exact copies of the original cells

What is chromatin?

a combination of DNA and protein molecules

What are chromosomes and how are the formed?

they are formed when chromatin coils up when it is about to divide - contains cell's DNA

Before DNA divides it duplicates its chromosomes and forms identical copies that make what?

sister chromatids

When the cell divides what separates?

the sister chromatids separate

Does every set have a complete and identical set of chromosomes?

yes

What are the 2 phases in the cell cycle?

interphase and mitotic phase

In what phase of chromosomes duplicate?

Interphase

In what phase do the cells divide?

mitotic phase

What is mitosis?

the division of the nuclei of cells - equal distribution of chromosomes into daughter nuclei

what happens in cytokinesis?

the cytoplasm divides into cells

list the stages of mitosis

Prophase, Metaphase, Anaphase, Telophase

What happens during prophase?

chromosomes condense, mitotic spindle forms (spindle apparatus composed of microtubles) that moves the chromosomes

what happens during metaphase?

chromosomes move to the equator of the cell

what happens during anaphase?

sister chromatids separate and move to opposite poles

what happens during telophase?

the cell begins to divide - mitotic spindle breaks down and cytokinesis occurs

what type of activities lower the chance of cancer?

not smoking, wearing sunscreen, exercising

In which stage does duplication occur?

Interphase

How does cytokinesis occur in animals?

by cleavage, it pinches the cell apart

How does cytokinesis occur in plants?

the cell plate splits in two

when the cell cycle functions normally, mitotic cell divisions work in what ways?

Growth, cell replacement and asexual reproduction

What does anchorage dependent mean?

normal cells divide only when they are attached to a surface

What does density dependence inhibition?

the cells continue dividing until they touch on another

what is the definition of cancer cells?

cells that divide excessively and can invade other tissues and displace normal cells

As a result of cancer how many people, in the US, will die this year (2017)?

500,000

what is the definition of a tumor?

an abnormal mass of cells

What type of "cancerous" cells do not spread?

benign

Do malignant tumors spread?

yes; they are cancerous

what is metastasis?

the growth of cancer cells beyond the original site

what are carcinomas?

cancers that originate in the external or internal linings of the body (ex. skin)

What are sarcomas?

they are in tissues that support the body - bone and muscle

What are leukemias and lymphomas?

they are in the blood forming tissues - bone marrow, spleen, lymph nodes

can humans use mitosis to reproduce?

No; that would be cloning

Are cancers usually affected by density dependent inhibition or anchorage dependent?

no

what is radiation treatment?

high energy radiation is used to destroy dividing cells - targets cancer cells, but can destroy normal cells

what is chemotherapy?

drugs that disrupt cell division cell division (ex. Taxol) impairs the functions of the mitotic spindle - discovered in the bark of the Pacific yew

what is sexual reproduction?

it produces genetic variety among offspring - inherit chromosomes from each parent

what are homologous chromosomes?

they carry genes controlling the same inherited characteristics - different versions of genes (alleles) code for different variations of characteristics

If a cell with 46 chromosomes divides in mitosis how many chromosomes will the resulting daughter cells have?

46

In humans, each homologous pair contains one chromosome inherited from who? and how many?

one from mom and one from dad

How many pairs of autosomes do humans have? and how many pairs of sex chromosomes?

22 pairs of autosomes and 1 pair of sex chromosomes

XX stands for what gender?

girl

XY stands for what gender?

boy

what do sex chromosomes do?

they determine the gender -- the male determines the gender of the baby

what are diploid cells?

two homologous sets of chromosomes (2n); in humans the diploid number is 46

what are gametes?

egg and sperm - haploid (single set of chromosomes) (n=23 in humans)

what is created when an egg and sperm fuse?

diploid zygote (2n=46)

what is meiosis?

cell division that forms gametes - reproductive organs

what is preceded by what?

interphase (chromosomes duplicate)

How many divisions occur in meiosis? How many haploid daughter cells are formed?

2 divisions occur and 4 haploid daughter cells are formed

How many duplications occur between the divisions in meiosis?

none

What happens in Prophase I in meiosis I?

In synopsis, homologous chromosome pairs come together and form a tetrad. These pairs exchange segments (crossing over). Spindle forms - tetrads start to move towards the center of the cell

What happens in metaphase I in meiosis I?

homologous chromosomes align on the metaphase plate

metaphase can also mean what?

middle

Are homologous chromosomes in Meiosis I or Meiosis II?

Meiosis I

Are sister chromatids in Meiosis I or Meiosis II?

Meiosis II

What happens in anaphase I in Meiosis I?

homologous chromosomes separate and move towards opposite poles

What happens in telophase I in Meiosis I?

chromosomes arrive at opposite ends of the cell and the cell divides in cytokinesis

what happens in prophase II in Meiosis II?

the spindle forms again

what happens in metaphase II in Meiosis II?

chromosomes align in the center of the cell (metaphase plate)

what happens in Anaphase II in Meiosis II?

sister chromatids separate and move to the opposite poles of the cell

what happens in Telophase II I Meiosis II?

chromosomes arrive at opposite poles and cytokinesis begins - forms 4 haploid cells when complete

what type of cells are being produced in Meiosis?

haploid cells

what is independent assortment (independent orientation)?

the segregation of alleles fro one gene does not affect the segregation of alleles for another

what is the smallest type of chromosome?

the y chromosome

Are all chromosomes different?

yes

2n equals what? What does n equal?

the number of possible combinations; n = the number of chromosomes in the gamete

In humans, how many possible combinations are in one gamete?

2^23 or about 8 million

What did many biologists believe in the 20th century?

That characteristic acquired during a lifetime could be passed onto the next generation and characteristics of both parents always blended in their offspring modern genetics began with Gregor Mendel's experiments with pea plants

Who crossed pea plants?

Mendel

List the 4 summary points of Mental's hypothesis?

1. There are alternative forms of genes = alleles

2. For each characteristics an organism has 2 genes, one from each parents

3. A sperm or egg carries only 1 allele for each trait

4. dominant and recessive alleles

If Y=yellow seeds and y= green seeds then what does Yy stand for?

yellow seeds

A father with AB blood is handed his new baby who has type O blood. If dad knows anything about biology, then why is this definitely not the happiest day of his life?

an AB type parents can't have an O blood type kid

Give an example of homozygous?

YY or yy

Give an example of heterozygous?

Yy

What does phenotype mean?

physical traits - ex. yellow seeds

What does genotype mean?

genetic makeup - ex. Yy

What does carrier mean?

someone who has an allele for a recessive trait but doesn't have the trait

P stands for what?

parental generation - parents

F1 stands for what?

first generation of offspring - kids

F2 stands for what?

offspring of F1 generation - grandkids

Monohybrid means what?

evaluate 1 trait

Dihybrid cross means what?

evaluate 2 traits

Y= yellow, y=green, S=smooth, s=wrinkled (square) if two plants that are heterozygous for both traits cross, then what promotion would you expect to have?

yellow, smooth

What is Autosomal Recessive Inheritance?

two recessive alleles must be present for the trait to be displayed

what are recessive disorders?

parents may be carriers ex. albinism, cystic fibrosis

What are dominant disorders?

they are carried on dominant alleles ex. achondroplasia, Huntington Disease (Hh- it's dominant so your child will have it)

(square) If a mom is homozygous for Huntington's disease what are the chances her son will have it?

100% - HH means the son is guaranteed to have it

(square) Two parents who have mild hypercholestedalemia have a daughter. What are the chances sh will have the sever form of the disease?

1/4

What is Codominance?

the expression of two different alleles of a gene in heterozygote (both genes are dominant)

Are ABO blood type codominance?

yes

List the forms of type A

I^A I^A or I^A i

List forms of Type B

I^B I^B or I^B i

List forms of Type AB

I^A I^B

list forms of Type O

ii

If a type O mother has a type O child then what could the father be?

I^A i or I^B i or ii

How many pairs of autosomes do humans have? and how many pairs of chromosomes?

22 pairs of autosomes and 1 pair of sex chromosomes