Unit 3 Biology

what is mitosis

mitosis is a type of cell division necessary for growth and repair

describe the cellular basis of cancer

cells replicate when they shouldn’t. results when regulation of the cell cycle fails.

unregulated cell division forms a lump of cells

compare and contrast benign and malignant tumors

benign: does not affect surrounding tissue

malignant: invades surrounding tissue (cancerous)

list several risk factors for cancer development that are under your control

cigarette smoking, alcohol consumption, UV light exposure

list the normal functions of cell division

growth: cell division enables organisms to grow by increasing the number of cells in their bodies

repair and replacement: it replaces damaged or dead cells, maintaining tissue health and function

reproduction:

asexual reproduction: cell division is the means of reproduction, genetically identical offspring

sexual reproduction: meiosis produces gametes with half the number of chromosomes which combine during fertilization to form a new organism

describe the structure and function of chromosomes

chromosomes: made of DNA wrapped around histone proteins

carry hundreds of genes

describe the events that occur during interphase of the cell cycle

normal cells most often in this step of the cell cycle

G1: organelles duplicate; cell grows

S: chromosomal DNA replicates

G2: cell grows and prepares for mitosis

describe the process of cytokinesis in animal and in plant cells

animal cells: a band of proteins encircles cells at the equator. proteins contract and pinch apart the original cell into two daughter cells

plant cells: vesicles deliver materials for the cell wall. cellulose-fibrous carbohydrate. proteins. vesicle membranes form a cell plate. cell plate and new cell wall grows as a barrier across the cell width

describe how mutations to genes that help regulate cell division can lead to tumor formation

mutations in tumor suppressor genes may lead to tumor formation

describe how chemotherapy, radiation, and immunotherapy destroy cancer cells

chemotherapy: chemicals that selectively kill dividing cells. injected into the bloodstream. normal diving cells are also damages: hair follicles, cells producing red and white blood cells, cells lining intestines, and stomach

radiation: use of high-energy particles to destroy cancer cells. used after surgical removal of the tumor or if surgery is not possible. usually for cancers close to the surface. damages DNA of remaining cancer cells

immunotherapy: immune system selectively destroys cancer cells. buildup the immune system to have the body fight off the cancer

what type of cells undergo meiosis

gametes undergo meiosis

explain the significance of crossing over and random alignment in terms of genetic diversity

crossing over: exchange of genetic information between homologous chromosomes

random alignment: members of homologous pairs are habitually arranged to face a pole

results in genetically diverse gametes

over 8 million possible alignments from 23 pairs of chromosomese

explain how altered meiosis affects fertility

impairing critcal processes in gamete formation, leading to chromosomal abnormalities and gamete loss

list the male reproductive structures and their functions

penis: delivers sperm to the female reproductive tract during intercourse

urethra: tube providing a way for sperm and urine to exit the body

scrotum: pouch containing the testicles

testes: produce sperm and androgens (male hormones)

seminiferous tubules: highly coiled tubes where sperm develop

epididymis: long, coiled tube atop each testicle for sperm to travel to vas deferens

vas deferens: duct that carries sperm to the urethra during ejaculation

seminal vesicles: glands that secrete mucus and sugars for energy

prostate gland: secretes a thin, milky white nutrient-rich fluid to the urethra

semen: made of sperm and all secretions. can survive up to 5 days in female reproductive system

list the female reproductive structures and their functions

vulva: all external genitalia

labia majora: thick folds of skin protecting labia minora

labia minora: think folds of skin enclosing the urethra, vaginal opening, and clitoris

clitoris: important organ for sexual arousal and orgasm

urethra: passageway for urine to exit from the bladder

vagina: receives sperm from the penis and serves as the birth canal

ovaries: produce egg cells and secrete estrogen and progesterone hormones

corpus luteum: remaining follicle after ovulation and secretes estrogen and progesterone

oviducts: duct carrying eggs from the ovary to the uterus

uterus: supports pregnancy and has a thick muscular wall that contracts during labor, childbirth, and orgasm

endometrium: the internal surface of uterine wall that changes during menstrual cycle

ccervix: lower third of uterus that produces stringy mucus to promote fertilizations

spermatogenesis — in general how does meiosis work in the uterus

cells lining seminiferous tubules undergo mitosis

one of the two daughter cells undergoes meiosis

other cells secrete substances for development and motility

oogenesis — in general how does meiosis work in the ovary

oogenesis: production of egg cells

ovulation: releasing the egg from the ovary

one egg per menstural cycled

describe the relationship between genes, chromosomes, and alleles

genes: segments of DNA that code for proteins

prokaryotes: single, circular chromosomes

eukaryotes: multiple linear chromosomes

chromosomes: a threadlike structure of nucleic acids and proteins found in the nucleus of most living cells, carrying genetic information in the forms of genes

alleles: different versions of genes produced by mutations

mutation effects may be neutral, beneficial, or dysfunctional

explain why, although each cell in your body contains identical genetic information, the cells produce by your body are different from each other

unique offspring through meiosis events

define segregation and independent assortment and explain how these processes contribute to genetic diversity

segregation: pairs of alleles separate into different gametes. gamete receives one copy of each manual page

independent assortment: homologous pairs separate into games, randomly and independently of other chromosomes. due to random alignment in meiosis 1

distinguish between homozygous and heterozygous genotypes and describe how recessive and dominant alleles produce particulat phenotypes when expressed in these genotypes

phenotype: physical traits of an individual

genotype: genetic compostion of an individual; describes alleles

demonstrate how to use a Punnett square to predict the likelihood of particular offspring genotype and phenotype from a cross of two individuals with known genotype

Punnett square: tabling listing possible gametes and predicting possible outcomes of a cross (mating between 2 parents)

differentiate incomplete dominance from codominance

incomplete dominance: a heterozygote expresses an intermediate “blended” phenotype. Ex: RR=red flowers rr=white flowers Rr=pink flowers

codominance: the heterozygote’s phenotype is a combination of two fully expressed traits. Ex: R1R1=red coat color R2R2=white coat color R1R2=red and white coat color

outline the pattern of inheritance seen in the ABO blood system

multiple allelism: more than two alleles of a gene are possible

describe the mechanism of sex determination in humans

23 pairs of human chromosomes

22 pairs of autosomes (nonsex chromosomes

one pair of sex chromosomes: women=two X chromosomes men=one X and one y

explain the pattern of inheritance exhibited by sex-linked genes

more common in either males or females

some traits due to genes on the sex chromosome

describe how DNA is organized

DNA double helix

DNA wrapped around histone

nucleosomes coiled into a chromatin fiber

further condensation of chromatin

duplicated chromosome

where do we find DNA?

blood, hair, nails, etc…

similarity of DNA between two people

you and the person next to you are only .60% different

any two humans differ by only approximately one alteration per 1,000 base paurs

describe the nature of polygenic and quantitative traits

polygenic traits: influenced by more than one gene. ex: eye color and skin color

quantitative triats: involves the actions of many genes also interacting with the envrionment

show continueaous variation: range of different phenotypes produced in a population with traits controlled by many genes

describe how heritabilty is calculated and what it tells us about the genetic component of quantitative traits

heritability: the amount of variation for a trait in a population that can be explained by differences in genes among individuals

estimated by using correlations with varying degrees of genetic similarity

explain why a high heritability still does not always mean that a given trait is determined mostly by the genes an individual carries

higher heritability only shows genes explain trait differences in a specific environment