BIO 111 UNIT 3 EXAM

gene

is a segment of DNA that carries the instructions for synthesizing a protein

gene's locus

a location on a chromosome

when 2 haploid sex cells fuse during fertalization, what is created?

a diploid zygote with 2 full sets of chromosomes

chromosome

member of a homologous pair of chromosomes

Gregor Mendel

used pea plants to study heredity

dominant alleles

exert their effects whenever they are present

recessive alleles

An allele that is masked when a dominant allele is present. usually encode nonfunctional proteins.

genotype

represents an individual's 2 alleles for one gene

phenotype

physical appearance; color or shape

punnett square

uses the genotypes of the parents to reveal which alleles the offspring may inherit

monohybrid cross

A cross between individuals that involves one pair of contrasting traits

when germ cells divide by meiosis-

-the gametes recieve one allele per gene

dihybrid crosses

track the inheritance of two genes at once

law of independent assortment

the law that states that genes separate independently of one another in meiosis

punnett squares and the product rule assume

2 genes are sorting independently

linked genes

physically near each other- therefore they do not sort independently

punnett squares and the product rule cannot be used if-

genes are linked

genes can become unlinked

during crossing over

crossing over

physically separates the 2 gene loci onto two different chromosomes

crossover frequencies

are used to find the relative positions of genes

incomplete dominance

the heterozygote has an intermediate phenotype

codominance

more than one allele encodes a functional protein

if 2 dominant alleles are present-

both proteins encoded by those alleles will be represented in the phenotype

pleiotropy

one gene has multiple effects on the phenotype

Epistasis

occurs when one gene's product affects the expression of another gene

x-linked recessive disorders

affects more males than females

each cell in an XX individual

randomly inactivates one X chromosome

Rett Syndrome

lethal to boys, has varying effects on girls

autosomal disorders

genetic disorders caused by genes on autosomes and can affect everyone

epigenetics

is a field of research that explores how cells adjust gene expression without altering underlying DNA sequence

polygenic trait

affected by more than one gene

How are meiosis, mitosis and fertalization involved in human life cycles?

Meiosis- sex cells Mitosis- regeneration, growth Fertalization- fertalization of sex cells to reproduce

Describe the importance of Mendel's work with pea plants. Why did he use peas?

His work showed how offspring can show clues about the genes of parents. He used pea plants because he could hand pollinate-this allowed him to control plant breeding experiments.

What are Mendel's two laws of inheritance AND how do they relate to what we now know about the process of meiosis?

independent assortment-what you get doesn't depend on anything else. law of dominance- if you have a dominant allele it will always be present. in meiosis I, the homologous chromosomes align randomly in their pairs- indepedent assortment.

How do sex-linked genes affect inheritance?

Dominant inheritance occurs when an abnormal gene from one parent can cause a disease, even though a matching gene from the other parent is normal. more likely to see sex-linked recessive disorders in males, because they only have the one X chromosome.

How can multiple genes or the environment can affect phenotype?

Through epigenetics- differences in lifestyle and experience can epigenetically influence gene expression and alter the chances of cancer, depression, addiction, and type 2 diabetes.

asexual production

does not require a partner and produces identical or nearly identical offspring

sexual reproduction

both parents contribute genes to the offspring, which are genetically unique

the gonads of sexually reproducing individuals produce ------- ------- by meiosis

haploid gametes

external fertilization

The process by which the female lays eggs and the male fertilizes them once they are outside of the female

internal fertalization

occurs when gametes unite inside the body of one of the parents

differentiate

acquire specialized functions

pattern formation

genes determine the overall shape and structure of the animal's body

indirect development

has an immature stage that looks different from the adult

direct development

have an immature stage that looks like a small adult

testes

The male gonads, which produce sperm and secrete male sex hormones.

seminiferous tubules

sperm production occurs in the walls of these tubules

steroli cells

surround, support, and nourish developing sperm cells

interstitial cells

fill the spaces between tubules and secrete male sex hormones

spermatogonia

divide by mitosis into primary spermatocytes

meiosis I yields

2 secondary spermatocytes

spermatocytes

cells in the testes that undergo meiosis

spermatids

formed from two secondary spermatocytes that undergo meiosis II to produce 4 of them

mature sperm cell

has a haploid nucleus, a long flagellum, mitochondria, and a cap like acrosome that helps it penetrate the egg cell

epididymis

A long, coiled duct on the outside of the testis in which sperm mature and are stored

vas deferens

a duct that passes above the urinary bladder and connects with an ejaculatory duct

seminal vesicle

secretes most of the fluid in semen

urethra

where sprem get to after traveling through the ejaculatory duct

prostate gland

surrounds the part of the urethra and secretes an alkaline fluid that activates sperm to swim

2 bulbourethral glands

also attatch to the urethra- secrete an alkaline mucus that prepares the urethra for sperm

ejaculation

the peni discharges semen from the body

the hypothalamus produces

GnRH (gonadotropin releasing hormone) which stimulates the antertior pituitary to release FSH and LH

FSH and LH

stimulate the testes to produce testosterone, cuing sperm production

ovaries

Glands that produce the egg cells and hormones

unterine tube

where eggs are collected

oogonia

cells that produce primary oocytes by mitotic division

each developing primary oocyte is nestled in a fluid-filled ____________

follicle

ovulation

meiosis I yields a secondary oocyte that is released from the ovary

corpus luteum

empty ovarian follicle that secretes progesterone after release of the egg cell

menstruation

when the uterus sheds its lining each month

the menstrual flow exits the body through

the uterus and vagina

where do fertilized eggs implant?

in the uterine lining

ovarian cycle

controls oocyte maturation in the ovaries

menstrual cycle

prepares the uterus for pregnancy

estrogen and progesterone

regulate menstrual cycle

progesterone

cues the uterine lining to thicken further

STI (sexually transmitted infection)

disease causing microbes move from host to host during sexual encounters

cleavage

a period of rapid cell division without growth

morula

solid ball of cells

blastocyst

hollow ball of cells

trophoblast

outer layer of blastocyst

placenta

an intricate connection between fetal and materal circulation

inner cell mass

The mass of cells in the blastocyst that ultimately give rise to the embryo and other embryonic structues (the amion, the umbilical vessels, etc.)

embryo

An organism in the earliest stage of development

implantation

the blastocyst digests and obtains nutrients from the uterine lining

hCG (human chorionic gonadotropin)

perserves the corpus luteum

embryonic disc

will develop into the embryo

ectoderm

outermost germ layer; produces sense organs, nerves, and outer layer of skin

endoderm

the inner germ layer that develops into the lining of the digestive and respiratory systems

mesoderm

middle germ layer; develops into muscles, and much of the circulatory, reproductive, and excretory systems

yolk sac

manufactures blood cells

allantois

gives rise to blood vessels in the umbilical cord

amnion

contains fluid that cushions the embryo and maintains constant temperature and pressure

chorion

the outermost membrane, produces chorionic villi that project into the uterine lining and exchange nutrients with maternal blood

umbilical cord

a tube containing the blood vessels connecting the fetus and placenta

primitive streak

an axis around which other structures organize as they develop

notochord

forms the framwork of the vertebral column

neural tube

a groove formed in the top layer of differentiated cells in the embryo that eventually becomes the brain and spinal cord

teratogens

substances that cause birth defects; alcohol, vitamins, prescription drugs, virsuses, etc.

How are genes related to differentiation of cells?

cells become unique based on which genes turn on and off