HSC Biology Mod 5

angiosperm

A flowering plant which forms seeds inside a protective chamber called an ovary.

Anther

In an angiosperm, the terminal pollen sac of a stamen, where pollen grains containing sperm-producing male gametophytes form.

artificial selection

Selection by humans for breeding of useful traits from the natural variation among different organisms

asexual reproduction

involves only one parent and produces offspring that are identical to the parent.

binary fission

type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells

Budding

A form of asexual reproduction of yeast and hydra in which a new cell grows out of the body of a parent.

clone

member of a population of genetically identical cells produced from a single cell

fertilisation

The fusion of 2 [haploid] gametes to form a [diploid] zygote.

Follicle-stimulating hormone (FSH)

secreted by the pituitary gland to stimulate maturation of the egg cell (ovum)

hCG (human chorionic gonadotropin)

pregnancy hormone which stimulates corpus luteum to develop and support growing embryo

LH (luteinizing hormone)

Produced by Anterior lobe of Pituitary Gland. Targets ovaries and testes to stimulate estrogen secretion and egg maturation; stimulates sperm production.

marsupial

A mammal, such as a koala, kangaroo, or opossum, whose young complete their embryonic development inside a maternal pouch called the marsupium.

monotreme

mammal that reproduces by laying eggs

Oestrogen

Female sex hormone which stimulates the lining of the womb to build up in preparation for a pregnancy.

Ovulation

The process of releasing a mature ovum into the fallopian tube each month

placental mammals

Mammals that nourish their unborn offspring through a placenta inside the female mammal.

Pollination

The transfer of pollen from anther to stigma in plants

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

Progesterone

hormone produced by the corpus luteum in the ovary and the placenta of pregnant women

hybridisation

the act of mixing different species or varieties of animals or plants and thus to produce hybrids

DNA structure

DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine

Chromatin

granular material visible within the nucleus; consists of DNA tightly coiled around proteins

Nucleoid

A dense region of DNA in a prokaryotic cell.

Chromosomes

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

nucleotide

A building block of DNA and RNA, consisting of a five-carbon sugar bonded to a nitrogenous base and a phosphate group.

sugar-phosphate backbone

The alternating chain of sugar and phosphate to which the DNA and RNA nitrogenous bases are attached

nitrogenous base

is a carbon ring structure that contains one or more atoms of nitrogen. In DNA, Adenine, Thymine, Cytosine, Guanine.

Histone

protein molecule around which DNA is tightly coiled in chromatin

Plasmid

A small, circular section of extra DNA that confers one or more traits to a bacterium and can be reproduced separately from the main bacterial genetic code.

transcription

the process where the DNA sequence in a gene is copied into mRNA

translation

the process where genetic information coded in mRNA directs the formation of a specific protein at a ribosome

mRNA

type of RNA that carries instructions from DNA in the nucleus to the ribosome

codon

sequence of three bases on a strand of mRNA that provides genetic code information for a particular amino acid

anticodon

group of three bases on a tRNA molecule that are complementary to an mRNA codon

complementary base pairing

In DNA, T pairs with A; G pairs with C;

RNA, U pairs with A and G pairs with C

ribosome

organelles at which proteins are synthesized.

amino acid

building block of protein

nitrogenous bases

adenine, guanine, cytosine, thymine, uracil

deoxyribose

sugar in DNA

ribose

sugar in RNA

tRNA

type of RNA that carries each amino acid to a ribosome during protein synthesis

amino acids

building blocks of proteins

nucleus

the place where transcription takes place

RNA polymerase

enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template

coding strand

the strand of DNA that is not used for transcription and is identical in sequence to mRNA, except it contains uracil instead of thymine

template strand

the strand of DNA that specifies the complementary mRNA molecule

Hydrogen bonds in DNA

Bonds that form between the nitrogenous bases that form the "rungs" of the DNA ladder

peptide bonds

The bonds connecting amino acids together to form polypeptide chains.

protein

An organic compound that is made of one or more chains of amino acids and that is a principal component of all cells

Polypeptide

long chain of amino acids that makes proteins

Bacterial DNA

exists in the form of a single circular chromosome

gene expression

process by which a gene produces its product and the product carries out its function

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Allele

An alternative form of a gene.

Anaphase

the stage of meiotic or mitotic cell division in which the chromosomes move away from one another to opposite poles of the spindle.

cell cycle

series of events that cells go through as they grow and divide - interphase (G1, S, G2) followed by Mitosis

Centriole

structure in an animal cell that helps to organize cell division by organising the spindle fibres

Centromere

Region of a chromosome where the two sister chromatids attach

chiasmata

site of crossing over in chromosomes in prophase I of meiosis

complementary base pairing

In DNA, T pairs with A; G pairs with C;

RNA, U pairs with A and G pairs with C

crossing over

exchange of genetic material between homologous chromosomes during prophase I of meiosis

Cytokinesis

division of the cytoplasm to form two separate daughter cells

double helix

two strands of nucleotides wound about each other; structure of DNA

gene pool

All the genes, including all the different alleles for each gene, that are present in a population at any one time

genetic variation

The variety of different types of genes in a species or population.

Genome

All the genetic information in an organism; all of an organism's chromosomes.

Genomics

study of whole genomes, including genes and their functions

homologous chromosomes

Chromosomes that have the same sequence of genes, that have the same structure, and that pair during prophase I in meiosis.

Interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

Meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

Metaphase

Chromosomes line up in the middle of the cell, attached to the spindle fibres

Prophase

Chromosomes become visible, nuclear envelop dissolves, spindle forms

independent assortment (random assortment)

During the first stage of meiosis the arrangement of the pairs of homologous chromosomes on the spindle is at random with each chromosome acting independently. When these chromosomes are drawn to the poles of the cell during anaphase, this leads to many different combinations of paternal and maternal chromosomes. Independent assortment is an important source of genetic variation.

Telophase

the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

allele frequency

a measure of how common a certain allele is in the population

Autosome

chromosome that is not a sex chromosome

Carrier

A person who has one recessive allele for a trait, but does not have the trait.

codominant phenotype

observable trait that displays aspects from both alleles

incomplete dominance

Cases in which one allele is not completely dominant over another - a third phenotype is observed.

F1 generation

the first generation of offspring obtained from an experimental cross of two organisms

F2 generation

Offspring resulting from interbreeding of the hybrid F1 generation.

gene flow

Movement of alleles into or out of a population due to the migration of individuals to or from the population

Genotype

An organism's genetic makeup, or allele combinations.

Heterozygous

having two different alleles for a particular gene

Homozygous

having two identical alleles for a trait

Histone

protein molecule around which DNA is tightly coiled in chromatin

Law of independent assortment

Mendel's second law, stating that allele pairs separate from one another during gamete formation

Law of Segregation

first law of heredity stating that pairs of alleles for a trait separate when gametes are formed

Microsatellite DNA (STRs)

sequence of tandemly repetitive DNA, 10 to 100 base pairs long

pedigree analysis

Chart showing one trait being carried over many generations

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

sex chromosomes

X and Y chromosomes.

sex-linked inheritance (sex-linkage)

the general term for inheritance of genes on either sex chromosome

single nucleotide polymorphism (SNP)

A single base-pair site in a genome where nucleotide variation is found in at least 1% of the population.

PCR (polymerase chain reaction)

A laboratory technique for amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and nucleotides.

DNA profiling (DNA fingerprinting)

compares the most variable parts of genome (STRs, SNPs and VNTRs) among individuals using gel electrophoresis

DNA sequencing

determining the order of nucleotide bases in a gene or DNA fragment